Congress isn't the only legislative body up for grabs during the upcoming November midterms. Control of the nation's state legislatures are also being contested. And as we've seen in our other handicappings, it's shaping up to be a good year for Democrats.

According to our first handicapping of state legislatures this cycle, Republicans currently have more chambers at risk, 10, than the Democrats' seven. Connecticut's tied Senate is also at risk of a party switch.

That adds up to 18 competitive chambers at this point -- identical to the number of competitive chambers in 2014, which was the most recent election cycle to feature a strong partisan wave. It was the Democrats who were on the run back then, with 11 Democratic-held chambers rated competitive compared to just seven for the Republicans.

During past wave elections, we've tended to see additional chambers become vulnerable to a party switch as time goes on, almost always for the party facing the wave. So unless the political environment changes significantly, expect the number of competitive Republican chambers to rise as November approaches.

That'll be a big change from the past few cycles, during which Republicans have tightened their grip on the nation's state houses and senates.

Currently, the GOP holds more than two-thirds of the nation's legislative chambers -- 66 in all, compared to 31 for the Democrats. For housekeeping's sake, this tally counts New York's Senate as Republican and Alaska's House as Democratic; both states are led by bipartisan coalitions. Meanwhile, Nebraska's unicameral legislature, which is nonpartisan, isn't included in our count.

The consolidation of GOP control has been striking. As recently as the run-up to the 2010 election, the Democrats held a 62 to 36 advantage in chambers.

It's worth noting that the degree of Republican vulnerability in 2018 is less than it was for the Democrats in 2010, both in the sheer number of vulnerable chambers and in the degree of the partisan tilt. In 2010, we considered 25 Democratic chambers to be in play. Of course, that election was held prior to the post-2010 Census round of redistricting, which bolstered Republican legislative prospects in a number of previously competitive states. Those post-2010 lines continue to protect Republicans in many states, limiting Democratic options for flipping chambers this year.

Our Ratings Summary

As always, our assessment is based on interviews with dozens of state and national political sources. We rate chambers on the following scale: safe Republican, likely Republican, lean Republican, tossup, lean Democratic, likely Democratic and safe Democratic.

The categories labeled "lean" and "tossup" are considered competitive or in play. Chambers in either of the "likely" categories are not expected to change party control on Election Day, but it's possible that the minority party could net a non-trivial number of seats and nibble into the majority's margins.

All told, we rate five Republican-held chambers as tossups: the Colorado Senate, the Maine Senate, the New Hampshire Senate and House, and the New York Senate.

We rate an additional five GOP-held chambers as lean Republican -- not yet as vulnerable as the tossup chambers, but worrisome for the GOP nonetheless. Those chambers are the Arizona Senate, the Florida Senate, the Iowa House, the Michigan House and the Wisconsin Senate.

We don't rate any Democratic-held chambers as tossups for now, but we do consider seven of them to be in the lean Democratic category: the Alaska House, the Colorado House, the Connecticut House, the Delaware Senate, the Maine House, and the Washington Senate and House.

If historical patterns hold and the Democratic wave solidifies, we may eventually drop many of these Democratic chambers from the competitive category.

Finally, we rate the tied Connecticut Senate as a tossup.

Rating Held by D Held by R Total Lean Republican 0 5 0 Tossup 0 5 1 Lean Democrat 7 0 0 Total 7 10 1

Estimating Possible Gains

In a neutral political environment -- one without a partisan wave -- our handicapping might produce a net Democratic gain of two to three chambers. But Election Day 2018 is not shaping up to be a neutral political environment.

If a wave ultimately only favors the Democrats modestly, we might see a four- to seven-chamber gain for the Democrats. If a larger wave materializes, Democrats could take a bigger bite out of the GOP's state-by-state advantage: a net switch of eight to 14 chambers. But to make that latter scenario possible, Democrats would need to move a bunch of chambers we currently rate as likely Republican into the lean Republican or tossup category.

We see seven chambers currently rated likely Republican that are worth watching for possible movement toward the Democrats. They are: the Arizona House, the Iowa Senate, the Michigan Senate, the Minnesota House, the North Carolina Senate, and the Pennsylvania Senate and House.

All in all, Democrats have reason to feel optimistic about gains at this point. Still, it's worth injecting a note of caution. Even a net switch of 14 chambers toward the Democrats -- the absolute maximum shift we can envision at this stage of the campaign -- would still leave Republicans with a national edge in chambers of 52-46. So don't expect the Democrats to seize a majority of state legislative chambers in 2018 alone.

Ratings: State by State

Listed below these maps are our ratings, with state-by-state summaries.

The data for the current partisan breakdown in each chamber comes from the National Conference of State Legislatures; seats that are vacant or held by third-party politicians are not included in the totals.

ALABAMA

Senate: Projected Safe R; Current 27-7 R

House: Projected Safe R; Current 70-33 R

While Republicans ultimately hurt themselves by nominating Roy Moore in a losing bid for a U.S. Senate seat, the state is so red that it will take more than a Democratic wave to change the partisan status quo in the legislature.

ALASKA

Senate: Projected Safe R; Current 14-6 R

House: Projected Lean D; Current 22-18 D (cross-party coalition)

With Alaska's Senate safely in Republican hands, the Democrats look to maintain control of the House. It is currently governed by a narrow, Democratic-led coalition. If oil prices stay relatively high, as they are now, voters may be less likely to rock the boat and the status quo in the House could continue. If not, the chamber could move to tossup.

ARIZONA

Senate: Projected Lean R; Current 17-13 R

House: Projected Likely R; Current 35-25 R

Democrats are three seats away from flipping the Arizona Senate, and they feel good about Democratic voter enthusiasm. But to take control, they would have to unseat some battle-tested Republican lawmakers. They may be able to do it by seizing on education and teacher pay, an issue that Democrats have found resonant in states even redder than Arizona -- and that is already causing GOP Gov. Doug Ducey heartburn.

ARKANSAS

Senate: Projected Safe R; Current 23-9 R

House: Projected Safe R; Current 75-24 R

Democrats might be able to snag a few extra seats this fall, but the GOP's majorities are big enough to remain secure.

CALIFORNIA

Senate: Projected Safe D; Current 26-13 D

Assembly: Projected Safe D; Current 52-25 D

Democrats, who already possess lopsided control of both chambers in California, may be able to expand their margins slightly this fall, due to President Trump's unpopularity in the state.

COLORADO

Senate: Projected Tossup; Current 18-16 R

House: Projected Lean D; Current 36-29 D

The Democrats have high hopes of flipping the GOP-controlled Colorado Senate. If the open-seat gubernatorial race turns in the Democrats' favor, they could pull it off.

CONNECTICUT

Senate: Projected Tossup; Current 18-18

House: Projected Lean D; Current 79-71 D

The key question about Connecticut voting patterns this fall will be who the electorate dislikes the most: Trump or two-term Democratic Gov. Dannel Malloy. If anti-Trump sentiment wins out, then Democrats can probably seize full control of the currently tied Senate. But if voters are more preoccupied with Malloy, the GOP is still in the game -- at least in the Senate. There are four open seats, several of which will be hotly contested.

DELAWARE

Senate: Projected Lean D; Current 11-10 D

House: Projected Safe D; Current 25-16 D

It's hard to imagine the blue state of Delaware losing Democratic seats in 2018. But out of an abundance of caution, we'll keep the narrowly divided state Senate rated as competitive.

FLORIDA

Senate: Projected Lean R; Current 23-15 R

House: Projected Likely R; Current 75-40 R

For the first time in a quarter-century, Florida Democrats have a genuine chance of seizing control of a state legislative chamber - and they're acting like it, contesting more seats than they have in recent election cycles. While the Democrats stand a good chance of picking up seats in both chambers, they'd have to make up too much ground in the House to make it genuinely competitive.

The much closer Senate, though, should be in play. That said, the higher-profile Florida races on the ballot -- for governor and U.S. senator -- could drain money and attention away from legislative races. It's also not clear that the Democratic nominee for either office will have strong enough coattails to bring a new legislative majority with them. Not even Barack Obama was able to pull that off when he won the state twice. So to start, we give the Republicans a modest edge to keep control of the Senate.

GEORGIA

Senate: Projected Likely R; Current 37-19 R

House: Projected Likely R; Current 116-64 R

It's reasonable to expect some Democratic gains this fall, especially in the Atlanta suburbs where there's been some Democratic growth. Still, the margins in Georgia are too wide for Democrats to be optimistic about flipping either chamber in 2018. Continued demographic and partisan evolutions in the state could give the party some hope further down the road, though.

HAWAII

Senate: Projected Safe D; Current 25-0 D

House: Projected Safe D; Current 45-5 D

During the Trump era, Republican numbers have sunk to extreme lows in the Hawaii Legislature. In fact, the state House has already seen one of its few Republican lawmakers switch to the Democratic Party, specifically naming Trump as the reason for the move. These are two of the safest Democratic chambers in the nation.

IDAHO

Senate: Projected Safe R; Current 29-6 R

House: Projected Safe R; Current 59-11 R

There's a possibility of minor Democratic gains given the few GOP retirements and departures, but nothing big enough to change the makeup of either chamber.

ILLINOIS

Senate: Projected Safe D; Current 37-22 D

House: Projected Safe D Current 67-51 D

With Republican Gov. Bruce Rauner facing a rough reelection battle -- and with the state unhappy with Trump -- this doesn't look like the year for Republicans to make significant gains in either chamber. A bonus for Democrats is that gubernatorial nominee J.B. Pritzker is heavily funding his own campaign, leaving pro-Democratic outside groups able to devote their money and time to shoring up control of the legislature.

INDIANA

Senate: Projected Safe R; Current 41-9 R

House: Projected Likely R; Current 70-30 R

The GOP edge in the Indiana Senate is big enough to withstand even a Democratic hurricane, but it's possible that Democrats could gain some modest ground in the House, especially due to Republican retirements and a series of intraparty challenges supported by the aggressively anti-abortion group Hoosiers for Life. Still, both chambers will remain in Republican hands.

IOWA

Senate: Projected Likely R; Current 28-20 R

House: Projected Safe R; Current 59-41 R

The GOP remains favored in the House -- the more vulnerable of Iowa's two chambers -- but Democratic enthusiasm and several retirements could make it interesting. The competitive gubernatorial race hasn't really heated up yet, so the battle for the legislature remains hard to handicap.

KANSAS

Senate: No Races; Current 31-9 R

House: Projected Safe R; Current 85-40 R

The Kansas House, the only chamber to be contested this fall, will remain in Republican hands. But if moderate Republicans manage to gain enough ground, they can work with Democrats to shape key bills.

KENTUCKY

Senate: Projected Safe R; Current 27-11 R

House: Projected Safe R; Current 63-37 R

Kentucky, which has all but completed its transition into a solidly Republican state, is not promising territory for Democrats to gain back legislative ground, even in a favorable year like 2018. Expect continued Republican control in both chambers.

LOUISIANA

Senate: 25-14 R

House: 61-41 R

Neither chamber in Louisiana is contested this year.

MAINE

Senate: Projected Tossup; Current 18-17 R

House: Projected Lean D; Current 74-70 D

Both gubernatorial primaries in June are crowded and unsettled. What's more, there are several credible third-party contenders. Given the uncertainty, we're rating Maine's Senate a tossup and the House lean Democratic. However, if Democrats look strong in the race for governor -- an office the GOP has controlled for eight years -- that could change our view.

MARYLAND

Senate: Projected Safe D; Current 32-14 D

House: Projected Safe D; Current 91-50 D

Both chambers in Maryland are solidly Democratic. The only issue is whether Republican Gov. Larry Hogan -- who's popular in the state despite his party affiliation -- can help oust enough incumbents to sustain vetoes. Currently, both chambers are veto-proof; the Democrats have more than the 85 representatives and 29 senators they need to override Hogan's vetoes.

MASSACHUSETTS

Senate: Projected Safe D; Current 31-7 D

House: Projected Safe D; Current 121-34 D

Bank on it: Massachusetts' lopsidedly Democratic chambers will be solid in 2018.

MICHIGAN

Senate: Projected Likely R; Current 27-10 R

House: Projected Lean R; Current 63-46 R

In the Senate, 27 of 38 seats will be open due to term limits, most of them Republican. Still, it's unclear at this point whether Democrats can win enough of them to flip the chamber this fall. But if they gain momentum as the cycle progresses, we may move it a notch.

In the House, a smaller percentage of seats are open, but there are about an equal number of seats that are marginally Democratic and marginally Republican, boosting the Democrats' odds of seizing the lower chamber.

MINNESOTA

Senate: No Races; Current 34-33 R

House: Projected Likely R; Current 77-57 R

Minnesota has lots of big races on the ballot this fall -- two U.S. Senate seats, several competitive U.S. House seats and all statewide offices, including the governorship. At the same time, the GOP will have to defend a bunch of competitive House seats, primarily in the Twin Cities suburbs. If a Democratic wave develops, we may push the House to lean Republican.

MISSISSIPPI

Senate: 33-19 R

House: 73-48 R

Neither chamber in Mississippi is contested this year.

MISSOURI

Senate: Projected Likely R; Current 24-9 R

House: Projected Likely R; Current 115-47 R

Missouri's Republican governor, Eric Greitens, is facing charges stemming from alleged sexual impropriety and may be impeached. Could Democrats benefit from a backlash? Maybe. But the GOP's margins are too big, it seems, to lose control in one cycle.

MONTANA

Senate: Projected Safe R; Current 32-18 R

House: Projected Safe R; Current 59-41 R

While Trump's popularity in the state has waned somewhat in recent months, it's not likely to affect legislative races in Montana.

NEBRASKA

Senate: Unicameral/Nonpartisan

Nebraska's unicameral legislature is officially nonpartisan, so we don't handicap it.

NEVADA

Senate: Projected Likely D; Current 11-9 D

Assembly: Projected Likely D; Current 27-15 D

In the Senate, despite the tight margin, Democratic incumbents look solid. The Assembly, meanwhile, doesn't appear to have enough vulnerable Democratic seats to flip, either.

NEW HAMPSHIRE

Senate: Projected Tossup; Current 14-10 R

House: Projected Tossup; Current 218-175 R

In recent election cycles, New Hampshire has been one of the nation's most closely divided and swingiest states. A flip to Democratic control is quite possible, but it's still early. What is certain is that both chambers will be competitive this fall. For now, we'll put them at tossup.

NEW JERSEY

Senate: 25-15 D

Assembly: 52-26 D

Neither chamber in New Jersey is contested this year.

NEW MEXICO

Senate: Projected Safe D; Current 26-16 D

House: Projected Safe D; Current 38-32 D

New Mexico is a state where the Democrats can expect a boost this fall. With Democrats already in control of both chambers, modest gains are possible.

NEW YORK

Senate: Projected Tossup; Current 32-31 R (cross-party coalition)

Assembly: Projected Safe D; Current 102-37 D

Special elections on April 24 gave state Senate Democrats -- long the chamber's minority -- a numerical edge. But it didn't matter, since one Democrat, Simcha Felder, said he would continue to caucus with the GOP. If Democrats run strong in November, his decision may be irrelevant. Still, there's enough murkiness that we're keeping this in the tossup category for now.

NORTH CAROLINA

Senate: Projected Likely R; Current 35-15 R

House: Projected Likely R; Current 75-45 R

The Democrats are poised to pick up seats in both chambers in North Carolina, especially in the House. But either way, there would have to be a significant wave for the GOP to lose control. The more urgent question is whether the Democrats can pick up enough seats to break the GOP supermajority in either chamber, handing Democratic Gov. Roy Cooper a weightier veto threat. In the House, the Democrats would need to net four seats to break the supermajority and would need six in the Senate.

Democrats are hoping that without a marquee statewide election on the ballot, turnout will be relatively low, giving them a boost. Moreover, by fielding more candidates than in the past, the Democrats should be able to take advantage of wave conditions. As in other states, suburban legislative districts could be decisive, particularly seats in populous Wake and Mecklenburg counties, which include Raleigh and Charlotte, respectively.

NORTH DAKOTA

Senate: Projected Safe R; Current 38-9 R

House: Projected Safe R; Current 81-13 R

North Dakota's strong Republican margins are not in danger of eroding this year.

OHIO

Senate: Projected Safe R; Current 24-9 R

House: Projected Likely R; Current 66-33 R

Only half the seats in the Ohio Senate are up in any cycle, which makes it less susceptible to wave conditions. The House is a bit more vulnerable (and is being buffeted by scandal and leadership squabbles). But the GOP edge in the House is wide and should be able to survive even a sizable Democratic wave.

OKLAHOMA

Senate: Projected Safe R; Current 40-8 R

House: Projected Likely R; Current 72-28 R

The Oklahoma Senate is certain to stay in Republican hands, with only 24 of 48 seats up this cycle and a big GOP edge. But dissatisfaction with GOP Gov. Mary Fallin has been brewing, and a battle over education funding has energized Democrats. If any Democratic gains are to materialize, it's likelier to happen the House. But for now, Republican dominance does not seem to be seriously threatened.

OREGON

Senate: Projected Safe D; Current 17-13 D

House: Projected Safe D; Current 35-25 D

The Democratic margins in the Oregon Legislature are modest, but it's a blue enough state in a blue enough year to be considered safe for now. Democrats may even be able to secure the one seat in each chamber that they need to gain a three-fifths supermajority. Going in the Democrats' favor is that the most competitive seats are in districts where Republican incumbents are leaving and where Democrats have been gaining ground.

PENNSYLVANIA

Senate: Projected Likely R; Current 34-16 R

House: Projected Likely R; Current 119-81 R

The Democrats should be able to gain seats in both chambers. Party strategists believe they have a path to taking over the state House this year, but it's premature to say that's a likely outcome. It's worth remembering that unlike the congressional district map, which was recently overturned by the state supreme court as an invalid partisan gerrymander, the lines in both state legislative chambers remain favorable to the GOP.

RHODE ISLAND

Senate: Projected Safe D; Current 33-4 D

House: Projected Safe D; Current 64-11 D

Despite a competitive gubernatorial race, the large Democratic majorities in the state legislature look solid for 2018. That said, there could be an ideological shift to the left within the Democratic caucus.

SOUTH CAROLINA

Senate: No Races; Current 28-18 R

House: Projected Safe R; Current 79-44 R

In the House, the GOP will be in good shape to retain its sizable majority, with only modest, if any, erosion.

SOUTH DAKOTA

Senate: Projected Safe R; Current 29-6 R

House: Projected Safe R; Current 60-10 R

The Republicans are in no danger of losing significant ground in this solidly red state.

TENNESSEE

Senate: Projected Safe R; Current 28-5 R

House: Projected Safe R; Current 74-25 R

There may be a few more seats than usual in play in Tennessee, and former Democratic Gov. Phil Bredesen is making a credible run for an open U.S. Senate seat. But significant Democratic gains look unlikely for now.

TEXAS

Senate: Projected Safe R; Current 20-11 R

House: Projected Likely R; Current 93-56 R

Even though Democrats are excited about Beto O'Rourke's chances at knocking off Republican U.S. Sen. Ted Cruz, don't expect major Democratic gains in the legislature. In the Senate, only one seat is considered genuinely in play, and that district leans Republican.

Democratic gains are likelier in the House, where Democrats are contesting an unusually large number of seats. That said, a double-digit increase seems like a stretch. Perhaps more important is the question of who might succeed the retiring speaker, Joe Straus, a moderate Republican backed by a mix of Democrats and Republicans.

UTAH

Senate: Projected Safe R; Current 24-5 R

House: Projected Safe R; Current 62-13 R

Democrats might be able to make some marginal gains, but Utah Republicans are in no danger of losing significant clout.

VERMONT

Senate: Projected Safe D; Current 21-7 D

House: Projected Safe D; Current 83-53 D

Democrats will hold on to both chambers in Vermont. The most pressing question is whether Republicans lose more than two seats in the House, a result that would leave them with too few votes to sustain a veto by GOP Gov. Phil Scott.

VIRGINIA

Senate: 21-19 R

House: 51-49 R

Virginia does not have elections this year.

WASHINGTON STATE

Senate: Projected Lean D; Current 26-23 D

House: Projected Lean D; Current 50-48 D

Both chambers in Washington state should remain blue this fall. Still, given narrow margins, we're keeping both chambers lean Democratic.

WEST VIRGINIA

Senate: Projected Likely R; Current 22-12 R

House: Projected Safe R; Current 64-36 R

West Virginia remains Trump country, and the GOP's margins in both chambers are sizable. Democratic gains, if any, will be minor.

WISCONSIN

Senate: Projected Lean R; Current 18-14 R

Assembly: Projected Likely R; Current 63-35 R

Democrats are optimistic about their chances in the state Senate, where they only need to net three seats to take control. The Democrats flipped one GOP-held Senate seat earlier this year, and on June 12 they hope to flip another. If they succeed, we may shift the chamber from lean Democratic to tossup.

By contrast, the GOP's margin in the Assembly should be large enough to hold, despite the possibility of some modest losses.

WYOMING

Senate: Projected Safe R; Current 27-3 R

House: Projected Safe R; Current 51-9 R

The Republican majorities in Wyoming have nothing to worry about in 2018.