If Democrats do have a chance to win the House next year, it might be because they translated a currently big field of announced candidates into credible opportunities to flip not just some of the top seats on their list of targets, but also some seats that, on paper, might not seem like they should be competitive. If that’s what happens — a big if at such an early point in the cycle despite President Trump’s unpopularity and the usual midterm trends that favor the party that does not hold the White House — it would mirror what happened when the Democrats last won the House from Republican control in 2006.

That year, Democrats ended up netting 31 seats, but they were not exactly the 31 seats that many might have thought would flip going into the election.

Several embattled GOP incumbents from districts that Democratic presidential nominee John Kerry had won or came very close to winning in 2004 ended up eking out close victories in 2006, including Reps. Chris Shays (R, CT-4), Heather Wilson (R, NM-1), Deborah Pryce (R, OH-15), and Jim Gerlach (R, PA-6). Had one known before the election that all four of these Republican incumbents would have won, it would have been reasonable to question the Democrats’ ability to net the 16 seats they needed to win the majority.

And yet, Democrats ended up gaining double what they needed, in large part because while they didn’t win all of the most obviously competitive races, they won some upsets through good performances by unheralded challengers. For instance, then-college professor Dave Loebsack (D) surprisingly knocked off Rep. Jim Leach (R, IA-2) and social worker Carol Shea-Porter (D), who defeated a candidate backed by the Democratic Congressional Campaign Committee in her party’s primary, upset Rep. Jeb Bradley (R, NH-1).

As we unveil our latest House ratings changes this week, we’ve been thinking about 2006 and the importance, to Democrats, of fielding as many credible challengers as they can. That’s because even if there is a positive environment for Democrats next fall, they are not going to knock off every clearly vulnerable GOP incumbent. Many Republicans who sit in districts that Hillary Clinton won last fall are proven vote-getters who ran well ahead of President Trump last fall, like Reps. Mike Coffman (R, CO-6), Carlos Curbelo (R, FL-26), Barbara Comstock (R, VA-10), Dave Reichert (R, WA-8), and others. Democrats probably will have to beat some of these incumbents in 2018 to win the House — or hope that some decide not to run for another term, like Clinton-district Rep. Ileana Ros-Lehtinen (R, FL-27) — but defeating all of them is unrealistic. Hence, the necessity of expanding the map.

The early returns for Democrats in that regard are favorable. Earlier this week, the Campaign Finance Institute’s Michael Malbin, writing for the Brookings Institution, chronicled how many Democratic challengers have emerged so far. The numbers, particularly compared to recent cycles, are eye-popping. See Chart 1, which is reprinted with permission from Malbin’s piece and uses Campaign Finance Institute data.

Chart 1: Campaign Finance Institute analysis of number of House challengers at comparable points of recent campaign cycles

At this point in the cycle, Democrats have more than 200 filed House challengers who have raised at least a small amount of money ($5,000 or more). That’s more than the combined total of Democratic challengers at this point of the cycle in the last four cycles, and way more than either party has had in midsummer of the off year over the last decade and a half.

Granted, $5,000 raised and being registered with the Federal Election Commission isn’t a tremendously high bar, but the early wave of candidates is striking compared with previous cycles. Additionally, as Malbin writes, the candidates are not necessarily clustered in the same districts: “So far, 105 different Republican incumbents have Democratic challengers with $5,000. At this same time in 2009, only 50 of the Democratic incumbents were up against challengers with $5,000.”

However, there are some packed fields already, too. For instance, Democrats kicked off their 2018 campaign message in Berryville, VA, earlier this week, which is in VA-10, held by the aforementioned Rep. Comstock. This is a district — Clinton won it by 10 points — that is a major Democratic target. However, party leadership’s preferred candidate, state Sen. Jennifer Wexton (D), actually finished behind three other Democrats in fundraising in the past quarter. Democrats also already have big fields in some races in California, which uses a top-two primary system to determine general election contests. All candidates, regardless of party, run in the primary, and the top-two vote-getters advance to November. It’s possible that big Democratic fields could lead to Republican incumbents in targeted districts advancing to the general election against another Republican, which has happened to Democrats in a couple of targeted races in recent years (and also to Republicans in the state’s U.S. Senate race last year). The Democratic Congressional Campaign Committee reserves the right to get involved in primaries: Will it do so in a major way next year? And, if the DCCC does, will it upset activists who distrust party leadership and believe that party bigwigs tilted the scales against Bernie Sanders in last year’s presidential primary? If Democrats begin to recoil at party leadership, the Democratic establishment might have to navigate through the same intraparty battles that sometimes bedeviled Republicans in the Obama years.

New candidacies, circumstances prompt ratings changes

The proliferation of Democratic candidates has led to some ratings changes this week:

Table 1: Crystal Ball House ratings changes

Democrats have long hoped New York state Assemblyman Anthony Brindisi (D) would run for Congress, and he recently took the plunge against first-term Rep. Claudia Tenney (R, NY-22), who won a spirited three-way race last year to take over for the less conservative, now-retired Rep. Richard Hanna (R). The district swung hard to Trump last year, going from essentially a presidential tie in 2012 to a 15-point Trump win. But upstate New York can be awfully swingy and Brindisi is a real challenger, prompting us to shift that contest from Likely Republican to Leans Republican.

Also moving with Tenney from the Likely to Leans Republican category are four additional northeastern members: Reps. Leonard Lance (R, NJ-7), Rodney Frelinghuysen (R, NJ-11), Ryan Costello (R, PA-6), and Pat Meehan (R, PA-7). All have one or more Democratic challengers and all saw Trump run behind Mitt Romney’s 2012 showing in their swingy districts. In Pennsylvania, PA-6 and PA-7 may be more competitive next year than Rep. Brian Fitzpatrick’s (R, PA-8) district, which seemed to be more of a swing seat when Republicans drew it following the 2010 census. As of now, Fitzpatrick, a freshman who replaced his retired brother last fall, does not have a clear Democratic challenger.

Moving from the Northeast to the Southwest, two incumbent Republicans move from Leans Republican to Toss-up.

From 2010-2014, AZ-2 was arguably the most competitive House seat in the entire country, narrowly reelecting then-Rep. Gabrielle Giffords (D) before the 2011 shooting that eventually prompted her retirement, then electing Ron Barber (D) in both a special election and a razor-thin general election in 2012. Barber’s 2012 challenger, now-Rep. Martha McSally (R), won a rematch with Barber in 2014 in another very tight race.

McSally, a prodigious fundraiser, won a relatively comfortable victory in 2016 after national Democrats largely ceded her the district, but the seat appears to be more of Democratic priority this time. One of McSally’s potential challengers is former Rep. Ann Kirkpatrick (D, AZ-1), who moved south after she lost a Senate challenge to Sen. John McCain (R-AZ) last cycle. Despite McSally’s war chest, the potential for a strong Democratic challenger emerging paired with a national Democratic commitment here makes us think that AZ-2 could easily revert to its usual level of competitiveness.

Out on the West Coast in and near Orange County, CA, Democrats are targeting several long-time Republican seats that shifted left at the presidential level last year. Their best opportunity is in CA-49, where Rep. Darrell Issa (R) barely hung on last year. But also intriguing, both because of changes in the district and the quirkiness of the incumbent himself, is CA-48, held by long-time Rep. Dana Rohrabacher (R). While Clinton did better in some other Republican-held area seats, CA-48 may be one place where the Trump campaign’s potential connections to Russia may have salience given Rohrabacher’s often-expressed warmth toward the Kremlin. Democrats are also excited by the candidacy of stem cell pioneer and businessman Hans Keirstead (D), although he has several other competitors for what would amount to the Democratic nomination. Some California analysts are skeptical that Democrats have a real shot at districts like CA-48 because of those districts’ longstanding and deep non-Trump Republican DNA and the turnout problems that Democrats sometimes have in midterms in California. For those reasons we’re holding a couple of other Orange County Democratic targets, Reps. Ed Royce (R, CA-39) and Mimi Walters (R, CA-45), at Likely Republican. But we see Rohrabacher as more vulnerable, perhaps significantly so, both because of his own liabilities and his potential challengers. One red flag for Democrats: A second Republican has entered the race in addition to at least four credible Democrats (Keirstead being one of them). It’s not impossible that Rohrabacher and the other Republican, businessman Stelian Onufrei, could advance to the general election if the Democrats splinter the Democratic primary vote and finish outside of the top-two slots, creating an all-Republican November matchup.

Five other districts come onto the board this week as Likely Republican. One of them is an open seat, NM-2, which Rep. Steve Pearce (R) is leaving to run for governor. Pearce did something similar in 2008 when he unsuccessfully ran for Senate, and Democrats won his open southern New Mexico seat despite its GOP lean. Pearce then won it back in 2010. It’s possible that something similar could happen, but the Republicans remain heavily favored there and some decent Republican candidates are already stepping up. This move is more out of an abundance of caution than anything else: Open seats defended by the president’s party can be susceptible to giant swings to the opposite party in midterms, but it would take a mighty swing in this seat for it to flip. The other four new Likely Republican seats are held by Reps. Mike Bost (R, IL-12), Andy Barr (R, KY-6), Tom Garrett (R, VA-5), and Scott Taylor (R, VA-2). All represent districts that are both right of center but that Democrats have held in the recent past. Perhaps the most notable seat on this list is IL-12 in Southern Illinois: Democratic recruit Brendan Kelly, the St. Clair County state’s attorney, has been a rumored candidate before but, like Brindisi, is taking the plunge this cycle in a seat that swung right at the presidential level last year.

With these ratings changes, there are now 26 Republican districts in the competitive Toss-up and Leans categories (that total includes the open FL-27, which we list as Leans Democratic and the only seat so far where the incumbent party is a clear underdog to hold a seat). So Democrats can look at that list and say that if they can win the Toss-ups and Leaners, they will win the House because they need to net just 24 seats to take control. That’s technically true, but, as argued above, it’s not really realistic: Even in a horrible GOP year, Democrats won’t sweep all of the top-tier races. They didn’t in 2006, nor did Republicans in 2010: even in the midst of that 63-seat net gain, Republicans failed to dislodge some clear targets, like Reps. Jerry McNerney (D, CA-11), Bill Owens (D, NY-23), and Mark Critz (D, PA-12).

That’s where the big playing field comes into play — if the Democrats can turn some Likely and Safe Republican seats into pickups next fall. They have some warm bodies running in those seats, but whether any can spring upsets will have a lot to do with their own performance and the national environment. That environment is promising for Democrats right now — for more on that, see some metrics compiled by Republican lobbyist Bruce Mehlman in his always-interesting quarterly report — though that’s not guaranteed to last or to make enough of a difference in some of these seats.

And Democrats also won’t be able to afford many, if any, losses of their own next year. Which brings us to the final ratings change.

Now that first-term Rep. Jacky Rosen (D, NV-3) is challenging Sen. Dean Heller (R-NV), her Trump-won swing seat moves from Leans Democratic to Toss-up. Republicans don’t have a lot of targets next year, which is to be expected given their healthy majority and the usual presidential-party challenges in a midterm. But they do have two open, Trump-won seats to target — MN-1 and NV-3 — and they have new, promising challengers against a few Democratic incumbents who won close races last year, like Reps. Stephanie Murphy (D, FL-7) and Rick Nolan (D, MN-8). Just playing a little bit of offense could provide a buffer for Republicans next year.

Table 2 shows our current House ratings. Remember, any seat not listed is safe for the incumbent party, so 187 Republican seats and 173 Democratic seats are Safe. That’s 360 of 435 seats (83%).

By far the biggest category is “Likely Republican,” reinforcing the idea that there is the potential for Democrats to create a broad-based wave against the GOP next year, particularly if the party continues to add new challengers. But it’s also way too soon to know whether many — or few — of these seats will really become competitive in 2018.

Table 2: Crystal Ball House ratings