KEY POINTS FROM THIS ARTICLE

— Of the 34 Senate races on the ballot in 2020, Republicans already control 22 of them while Democrats hold only 12. That represents something of a role reversal from 2018, when Democrats had to defend 26 of 35 seats being contested.

— Still, Republicans start this cycle favored to hold the Senate, but there is a plausible path for Democrats, particularly if Democrats win the presidential race.

— The most vulnerable senator from either party is Sen. Doug Jones (D-AL), followed by Sen. Cory Gardner (R-CO). A special election in Arizona also starts as a Toss-up.

Initial Senate ratings for 2020

In the 2018 cycle, the big story was that the Democrats faced a historically difficult map of Senate races. They had to defend 26 of the 35 seats being contested, including Democratic incumbents in several dark red states. Ultimately, Democrats won 24 of the 35 races, nearly 70% of those on the ballot. But Republicans netted two seats overall, boosting their majority from 51 seats to 53 seats when the new Senate convenes next month. Democrats will hold 47 seats, a total that includes independent Sens. Angus King of Maine and Bernie Sanders of Vermont.

Overall, the 2018 results brought the Senate map further into partisan alignment. Going into the election, only 15 senators (out of 100) represented states that their party’s presidential candidate lost in the 2016 presidential election. Of those 15, 11 were on the ballot in 2018, and the results reduced the total number of crossover senators by four, to just 11 total. Republicans captured four Democratic-held seats in states that Donald Trump won in 2016 (Florida, Indiana, Missouri, and North Dakota), and Democrats won the only Republican-held seat that was contested in a state Hillary Clinton won (Nevada). Democrats also captured a Senate seat in Arizona, a Trump-won state. Meanwhile, Trump-state Democrats won reelection in Michigan, Montana, Ohio, Pennsylvania, West Virginia, and Wisconsin.

The current party control of the Senate by state is shown in Map 1.

Map 1: State-by-state Senate control starting in 2019

Map 1 demonstrates political patterns that largely reinforce other federal voting trends. The West Coast and New England have almost entirely Democratic Senate delegations, the South and Great Plains are almost uniformly Republican, and the Midwest is mixed, reflecting the region’s long-held battleground status.

Map 2 isolates the 34 Senate seats that are being contested in 2020. There are 33 regularly-scheduled elections, along with a special election in Arizona for the remaining two years of the term that the late Sen. John McCain (R-AZ) won in 2016. Three of these seats — Alabama, Minnesota, and Mississippi — were on the ballot as special elections during the 2018 cycle. So if Sens. Doug Jones (D-AL), Tina Smith (D-MN), and Cindy Hyde-Smith (R-MS) want full, six-year terms, and it appears that they all do, they will have to run again this cycle.

All told, Republicans are defending almost double the number of Senate seats in 2020 (22) as Democrats are defending (12).

Map 2: Current party control of Senate seats on the ballot in 2020

In order to win control of the Senate, Democrats will have to net at least three seats this cycle. If they did that, the Senate would have an even 50-50 split, with whoever the vice president is in 2021 breaking ties. Without the presidency, Democrats would need to net four seats to win a bare 51-49 majority. However, the Senate races and the presidential race probably will work at least somewhat in tandem, meaning that it’s hard to imagine Republicans holding the White House while simultaneously losing four net Senate seats. So winning the White House is likely a necessary but not sufficient condition for a Democratic Senate takeover. Our initial ratings for the 2020 races are shown in Map 3.

Map 3: Initial Crystal Ball 2020 Senate ratings

While Republicans are defending a large number of total seats, many of them should be easy GOP holds. In our initial ratings, more than half of the GOP seats — 13 of 22 — start as Safe Republican. That includes five of the nine Senate seats Republicans captured from Democrats in 2014, the last time this Senate map was contested: Alaska, Arkansas, Louisiana, South Dakota, and West Virginia. All five of these states are substantially Republican, which makes it difficult to imagine the Democrats clawing any of these states back in 2020. Additionally, Republicans start with a very clear edge in Idaho, Kansas, Mississippi, Nebraska, Oklahoma, South Carolina, Tennessee, and Wyoming. Collectively, this group has elected only one Democratic senator this century: Ben Nelson (D-NE), who won in 2000 and 2006 before retiring in 2012. It might be tempting to look at a state like Kansas, where Sen. Pat Roberts (R-KS) performed relatively weakly in both his 2014 primary and general election, as a dark horse Democratic target. The state did, after all, just elect a Democratic governor. But then one remembers that Kansas hasn’t elected a Democratic senator since 1932.

Meanwhile, seven of the 12 currently Democratic Senate seats start as Safe Democratic: Delaware, Illinois, Massachusetts, New Jersey, New Mexico, Oregon, and Rhode Island. So that means 20 of the 34 Senate seats on the ballot in 2020 begin as rated Safe for the incumbent party.

Let’s look at the remaining 14, many — but not necessarily all — of which will be competitive in 2020.

While on paper the Democrats need to capture at least three currently Republican Senate seats to take control of the Senate, realistically they probably need to win at least four. That’s not because of the presidential race; rather, it’s because Democrats are going to have a very hard time defending the Senate seat currently held by Sen. Doug Jones (D-AL), who won a December 2017 special election against former Alabama state Supreme Court Chief Justice Roy Moore (R), arguably the worst candidate either party has nominated for a hotly-contested Senate seat in recent memory. Jones beat Moore 50.0% to 48.3% in the special election despite Moore’s many problems. One would assume both that the GOP presidential nominee will carry Alabama by 20 points or more and that the GOP Senate nominee won’t be as weak as Moore. The 2018 Senate results, where Democratic incumbents lost in three heavily Republican states despite good national conditions, also augur poorly for Jones, who is running in a Deep South state that may be more Republican at its core than Indiana, Missouri, or North Dakota, the three dark red states where Democrats lost in November. Starting Alabama as a Toss-up probably is being kind to Jones, and he is clearly the most vulnerable senator on the ballot of either party. A host of Republicans are considering bids, including several state-level officeholders, Rep. Bradley Byrne (R, AL-1), and perhaps even former U.S. Attorney General Jeff Sessions, who held this seat for two decades prior to joining the Trump administration. Alabama seems likely to lose a GOP-held House seat after the 2020 census reapportionment, which could prompt other members of the state’s congressional delegation to take a look at this Senate race. Uncertainty about the quality of Jones’ 2020 challenger is the only thing keeping Alabama a Toss-up, although we also have learned that it is sometimes dangerous to write off an incumbent at the start of a campaign cycle.

Democrats start as at least small favorites in the four other plausible GOP targets on this map. Sen. Gary Peters (D-MI) is a fairly low-profile senator, although he did win what was in hindsight an impressive, double-digit victory in an open-seat race against former Michigan Secretary of State Terri Lynn Land (R) in 2014. That was notable because Trump very narrowly won the state two years later, and Sen. Debbie Stabenow (D-MI) turned in a relatively weak 6.5-point victory in her reelection last month, holding off a spirited challenge from veteran John James (R). James could run again, and he likely would need Trump or another GOP presidential nominee to once again carry Michigan to have a real chance to win. Trump reportedly considered James as the next ambassador to the United Nations, but he decided to nominate State Department spokeswoman Heather Nauert instead.

New Hampshire, one of the nation’s perennially competitive states, also is a plausible GOP target as Sen. Jeanne Shaheen (D-NH) considers whether to seek a third term. Gov. Chris Sununu (R-NH) would be a natural and formidable challenger, although he said back in 2017 that he would “never” run for the Senate, for what it’s worth. Former Sen. Kelly Ayotte (R-NH), a hard-luck loser in 2016, is another familiar GOP name in the Granite State who would be a credible Republican Senate nominee. Longer-shot Republican targets come in Minnesota, where Sen. Tina Smith (D-MN) likely will seek a first full term, and Virginia, where Sen. Mark Warner (D-VA) likely will seek a third term. Trump came close to winning Minnesota in 2020; if he somehow carried it, that probably would put Smith in danger, but it’s unclear whether she will face a top challenger. Meanwhile, the Democratic presidential nominee should be decently positioned in Virginia, which should insulate Warner, who got a real scare in the poor national Democratic environment of 2014. If either Smith or Warner is in significant trouble come November 2020, something likely is going seriously wrong for Democrats overall.

All told, Republicans have one really good target in the Senate in 2020 — Jones in Alabama — and probably uphill climbs in the other currently Democratic Senate seats on the ballot. But just one good target might be sufficient, because the Democratic Senate target list is like a cheap, all-you-can-eat buffet: long on options, but short on quality.

Democrats’ best two chances to win a currently GOP Senate seat in 2020 come in Arizona and Colorado, both of which we’re starting as Toss-ups.

Let’s start in the Centennial State, where at the very least we know with reasonable certainty the identity of the GOP nominee, as Sen. Cory Gardner (R-CO) is gearing up to seek a second term. Gardner won by two points over then-Sen. Mark Udall (D-CO) in the strong GOP environment of 2014. Gardner might have a harder slog in 2020, as Democrats appear to be gathering strength in Colorado. Clinton carried the state by about five points in 2016, and Democrats won the governorship for the fourth-straight cycle in 2018. Gardner might not need the Republican presidential nominee to carry Colorado in order to win, but remember that no state voted differently for president and Senate in 2016, the first time that has ever happened in the history of Senate popular elections. If the GOP presidential nominee can’t keep it very close in Colorado, Gardner is in real trouble. The Democratic field is unclear in the early going: Possibilities include Crisanta Duran, the outgoing, term-limited speaker of the state House of Representatives; two of the candidates who unsuccessfully sought the Democratic gubernatorial nomination last cycle, former state Treasurer Cary Kennedy and former state Sen. Mike Johnston; and possibly outgoing, term-limited Gov. John Hickenlooper, who probably will take a shot at running for president. Remember: Gardner didn’t enter the 2014 contest until late February 2014 after initially taking a pass on the race, so there’s plenty of time for Hickenlooper to dabble in the presidential race and, if it doesn’t work out, potentially reconsider a Senate bid.

In Arizona, Sen. Jon Kyl (R-AZ) has yet to announce whether he’s going to stay in the Senate after taking over for McCain earlier this year. After retiring from the Senate in 2013, Kyl has always seemed like a short-termer, and he may not even finish out his temporary appointment, which runs through the 2020 special election. Assuming Kyl leaves soon, Gov. Doug Ducey (R-AZ) will appoint another temporary senator. The appointee could seek the office, but remember that appointed incumbency does not confer the same advantages as elected incumbency. One possible appointee is outgoing Rep. Martha McSally (R, AZ-2), who lost to Sen.-elect Kyrsten Sinema (D-AZ) in November, although there’s some dispute as to whether Ducey would prefer to nominate someone else, like his now-former chief of staff, Kirk Adams (R), who might just be a caretaker if appointed. It would be ideal for national Republicans if the new appointee, if there is one and that person runs for the job, could at least deter a serious primary challenge. The late August primary can put a party nominee behind the eight-ball in Arizona, as arguably happened to McSally last cycle and some GOP House candidates over the last few cycles. It’s unclear who Democrats will nominate: Rep.-elect Greg Stanton (D, AZ-9), the former mayor of Phoenix, is a possibility. So too are former state Attorney General Grant Woods (D), a former Republican who was a McCain ally, and Rep. Ruben Gallego (D, AZ-7). Again, let’s see if there’s a primary on the Democratic side as well: Sinema benefited from a clear path to the nomination in 2018 that allowed her to build a positive statewide profile before GOP attacks started in earnest after McSally won the nomination. Arizona is still right of center, but the Democratic presidential nominee probably will make a play for the state, and the Democratic Senatorial Campaign Committee will assuredly try to field the strongest possible candidate. Whoever wins this race in 2020 will have to run again for a full term in 2022.

Four additional GOP-held seats start as Leans Republican in our ratings. Sen. Susan Collins (R-ME) is one of the two Republicans in Clinton-won states on the ballot this cycle (Gardner of Colorado is the other), and the Leans Republican rating mostly reflects some uncertainty about whether she’ll run again. If she decides to seek a fifth term, we might upgrade her to Likely Republican, as she still seems to have an enviable level of crossover appeal and Maine probably will be competitive statewide for president (Trump easily carried an electoral vote in Maine’s Second Congressional District, but Clinton carried the state overall by three points thanks to greater strength in the more liberal First District). Democrats are hopeful that Collins’ important role in the divisive Brett Kavanaugh nomination fight will make her a more partisan, and thus more vulnerable, figure, but it’s not clear as of now whether that has happened or will happen. A Collins retirement, meanwhile, would make this race a real Toss-up — and perhaps it’d become that anyway depending on whether perceptions of Collins have dramatically shifted and if a strong Democrat steps up against her. We’ll have to see whether Rep. Chellie Pingree (D, ME-1) decides to take the plunge. Sara Gideon (D), speaker of the state House of Representatives, is another possibility. Susan Rice (D), formerly the national security adviser to former President Obama, has tweeted interest in the race, although it’s unclear how serious she might be. Rice’s mother was from Maine and she’s spent a lot of time there, but she is from the Washington, D.C. area.

Assuming all the incumbents in the Leans Republican states run, the Democrats’ best target probably is Sen. Thom Tillis (R-NC), a narrow 2014 winner in a competitive presidential state that seems to throw out incumbent senators with regularity. The last two occupants of this seat, former Sens. Elizabeth Dole (R-NC) and Kay Hagan (D-NC), each failed in their attempts to win second terms. It’s unclear who Democrats might nominate, though: state Sen. Jeff Jackson (D) is a possibility. The presidential race probably will loom large in this contest: Democrats have hoped the state would become bluer, like its northern neighbor Virginia, because of demographic changes, but the Tar Heel State has consistently voted to the right of the nation for president over the last half century, except when southerner Jimmy Carter was the Democratic nominee in 1976 and 1980. North Carolina is more purple than it was a couple of decades ago, but it’s not a pure swing state, either, which gives Tillis a little bit of a cushion, at least to start.

In Iowa, Sen. Joni Ernst (R) was an impressive 2014 winner, and Trump would start as a favorite to carry the state again assuming he’s nominated after winning by a surprisingly large nine-point margin in 2016. That said, Iowa also elected two new Democratic House members in November, giving Democrats a three-to-one edge in the House delegation. One Senate possibility is former Gov. Tom Vilsack (D-IA), who also served as secretary of agriculture in the Obama administration.

Finally, Georgia seems to be becoming more competitive, although Republicans narrowly defended the open governorship earlier this year. Sen. David Perdue (R-GA) starts as a favorite, but a strong challenger could push him. Unsuccessful gubernatorial nominee Stacey Abrams (D) could run against Perdue.

Rounding out the list of potentially competitive Senate races are three final GOP-held states we’re starting as Likely Republican: Kentucky, Montana, and Texas. Senate Majority Leader Mitch McConnell (R-KY) has weak favorability numbers but the Bluegrass State may simply be too Republican to elect a Democrat to the Senate, something it hasn’t done since 1992. The 2019 governors’ race, featuring unpopular Gov. Matt Bevin (R), may tell us something about the gubernatorial race: If Bevin wins comfortably in a state-level race despite bad numbers, McConnell likely is unbeatable in a federal election held concurrently with the presidential race no matter what his approval rating may be. Sen. Steve Daines (R-MT) starts well-positioned, and very well could be upgraded to Safe Republican if term-limited Gov. Steve Bullock (D-MT) doesn’t challenge him. Bullock has said he is not interested in the Senate race and seems likely to at least dip his toe into the presidential waters, but Sen. Jon Tester (D-MT) recently suggested Bullock would run for Senate (Tester backtracked). Regardless, one would expect the DSCC will lean heavily on Bullock to consider a bid. So we’ll just have to wait and see. Meanwhile, Sen. John Cornyn (R-TX) is more of a generic Republican than Sen. Ted Cruz (R-TX), which might put him in a better position for reelection than the more polarizing Cruz, who only won in November by about 2.5 points over outgoing Rep. Beto O’Rourke (D, TX-16). O’Rourke might run for president; Democrats would assuredly love for him to run against Cornyn although, as one observer recently mentioned to us, “you can’t make a soufflé rise twice” (borrowing the quote from the witty Alice Roosevelt Longworth). Meaning: At least in terms of a Texas Senate race, Beto-mania might be hard to re-run, although perhaps if O’Rourke takes his act nationally he’d get some traction in a Democratic field that may have plenty of participants but not so much charisma. Cornyn should be OK, but Texas does seem to be getting more competitive, and Republicans should be concerned about their suburban performance across the state, which could endanger several House seats that have seemed safe in the past and, eventually, the state as a whole.

Conclusion

Overall, in order to win the Senate, Democrats probably will need to win Arizona and Colorado as well as at least a couple of the Leans Republican states: Georgia, Iowa, Maine, or North Carolina. That these crucial states begin with Republicans as small favorites points to a larger overall assessment: the GOP starts this cycle favored to hold the Senate. However, there is a plausible path for Democrats, particularly if a Democrat wins the presidency and provides some down-ballot coattails.