The road to a Democratic House of Representatives goes straight through Pennsylvania — which means this Tuesday’s primary is remarkably important for the party’s chances of retaking the chamber.

A serious chunk of the 23 net pickups Democrats need to retake the House could be found in Pennsylvania alone. The Cook Political Report deems seven Republican-held districts in the state as potentially competitive, with five of those either toss-ups or favoring Democrats already.

Democrats are likely to lose one seat they currently hold because Rep. Conor Lamb is switching to run in a different district. Still, if the party runs the table, it could get a quarter of the way toward winning the House through the Keystone State alone.

The stakes are so high in Pennsylvania because this year, it’s using a new congressional map — one imposed by the state Supreme Court, which threw out the map used for the 2012 through 2016 elections on the grounds that it was a pro-Republican partisan gerrymander. (For most of the decade, Republicans held a 13-5 House seat advantage in the swing state.)

The new map gives Democrats many more, and better, opportunities than the old one did. Additionally, three Republicans in districts that Hillary Clinton won are retiring or have already resigned. But to maximize their Pennsylvania pickups, Democrats need strong candidates. That’s what will be determined Tuesday — the slate of Democratic challengers in one of the most important House states in the country.

There are three Republican-held open seats in districts Clinton won

They left for different reasons — one due to a sexual harassment scandal, one due to the new map, and one out of general disgruntlement with the state of politics — but all three are plum pickup opportunities for Democrats.

The Cook Political Report lists two of them as the best pickup opportunities for House Democrats in the entire country, with the third not far behind.

Pennsylvania’s Fifth District: a very crowded primary for a near-certain Democratic pickup

This open seat in the southeast of the state was vacated by Republican Rep. Pat Meehan, who resigned due to accusations that he sexually harassed an aide. But it’s already a near-certain Democratic pickup — the new map changed this from a swing district to one Hillary Clinton won by 28 points.

So the main drama is which of the 10 Democratic candidates in the race will emerge triumphant in an incredibly crowded primary race — and no one really knows! Lawyer Mary Gay Scanlon and former prosecutor Ashley Lunkenheimer raised the most money, but a recent poll showed state Rep. Greg Vitali (who’s foresworn big-dollar fundraising) in the hunt too. With no obvious frontrunner, it’s entirely possible someone could win with less than 20 percent of the vote.

Whoever does pull that off will almost certainly be a member of Congress next year, unless the Republican candidate, Pearl Kim, pulls off a shocking upset.

Pennsylvania’s Seventh District: a three-way ideological showdown among Democrats

Perhaps the clearest ideological battle on the ballot for Democrats is in this Lehigh Valley district. There’s a wide-open race to succeed former Republican Rep. Charlie Dent, who co-chaired the House GOP’s moderate Tuesday Group but retired due to frustration with polarized politics.

And under the new map, Clinton won the district by 1 point, making it a prime pickup opportunity. Yet the leading Democratic candidates’ political profiles differ dramatically:

John Morganelli, the Northampton County district attorney, is well-known in the district — but he’s also anti-abortion, pro-gun, and has said harsh things about unauthorized immigration and positive things about Donald Trump. Democrats worry that Morganelli could win based on name recognition but prove an unreliable vote for the party in Congress. Greg Edwards is an African-American pastor supported by progressive activist groups, including the Bernie Sanders-aligned Our Revolution. Edwards publicly blasted the Democratic Congressional Campaign Committee when it inquired whether he’d consider running for state Senate instead. Susan Wild, the former Allentown city solicitor, is backed by Democratic women’s groups like Emily’s List and NARAL.

Republicans need a new candidate too, and on their side, former Olympic cyclist Marty Nothstein is facing off against businessman Dean Browning.

Pennsylvania’s Sixth District: Democratic Air Force veteran Chrissy Houlahan is strongly favored

Perhaps the single most damaging impact of the new map on Republicans’ House prospects was the redrawing of this district, represented by Republican Rep. Ryan Costello, to be one Hillary Clinton won by 9 points.

Costello was positively irate and decided he wouldn’t even bother to run again. But he did this after the filing deadline had passed, which prevented Republicans from recruiting a strong candidate. Instead, it seems the GOP will be stuck with Greg McCauley, a little-known attorney who happened to file beforehand, as their nominee.

Democrats, meanwhile, are positively thrilled about the candidacy of Chrissy Houlahan, who’s running unopposed in the primary. Houlahan is an Air Force veteran and a powerhouse fundraiser, and the party felt good about her prospects against Costello even under the old district lines. Now that she’s facing an obscure opponent in a more Democratic district, the Cook Political Report has already deemed this race “likely Democratic.”

Several other Republican incumbents will also face challenges

Beyond the three open seats, Democrats are taking aim at several other GOP incumbents in the state, with widely varying chances of success.

Pennsylvania’s First District: Hillary Clinton narrowly won the new version of this eastern district represented by Republican Rep. Brian Fitzpatrick, which puts it among the top Democratic targets.

The local party is backing Scott Wallace, a wealthy lawyer who’s already put $2.5 million of his own money into the race. He’s being challenged by Rachel Reddick, a former Navy prosecutor blasting him as a “Maryland multimillionaire.” Reddick has her own problem, though — she was a registered Republican until last year. Progressive activist Steve Bacher is also running.

Pennsylvania’s 17th District: Democrat Conor Lamb won a seat in Congress this March in a special election held under the old district lines. But in the reshuffling under the new map, he’s chosen to run against incumbent Republican Rep. Keith Rothfus. Both are unopposed in the primary, so there will be a rare showdown between two current members of Congress in the general election. And this southwestern district is much more Democratic than the one Lamb has already won in — Trump won it by just two and a half points.

Pennsylvania’s 10th District: Republican Rep. Scott Perry represents a district Trump won by about 9 points, making it more conservative than any mentioned so far but not entirely out of the question in a Democratic wave year. The top fundraisers on the Democratic side are public health scientist Eric Ding and former Capitol Hill and Obama administration staffer Shavonnia Corbin-Johnson.

Pennsylvania’s 16th District: This northwestern district represented by Republican Rep. Mike Kelly went to Trump by 20 points, but to Mitt Romney in 2012 by only 5 points — so the Cook Political Report deems it “likely Republican” rather than safe. Attorney Ron DiNicola is the leading fundraiser in the Democratic primary.

Pennsylvania’s 11th District: In a deeply conservative district Trump won by 26 points, Republican Rep. Lloyd Smucker is facing a primary challenge from the right, from Chet Beiler. Beiler has pledged to join the Freedom Caucus if elected. The Democratic nominee will be Jess King.

Pennsylvania’s 12th District: Republican Rep. Tom Marino is running for reelection in a district that Trump won by 36 points. But first, he has to win his primary, and that’s no sure thing. Marino was nominated as Trump’s drug czar last year, but he withdrew from consideration after reports described his role in passing a law that critics say hindered the government’s response to the opioid epidemic. So Bradford County Commissioner Doug McLinko (R) is challenging him in the primary on the issue.

On the Democratic side, drug and alcohol counselor Judy Herschel and Penn State professor Marc Friedenberg are competing for the nomination, though the district is believed to be safely in the GOP’s hands.

Democrats risk losing two seats to Republicans

Still, it’s not all upside for House Democrats in Pennsylvania this fall. One Democrat-held seat will likely flip to Republicans. Another Democratic incumbent is also facing a challenge

Pennsylvania’s 14th District: As mentioned above, Conor Lamb’s victory occurred under the old map, in a district that was split between the new 17th (where he’s running) and the more conservative new 14th. Trump won this new district by 29 points, so it will likely be, technically, a Republican pickup canceling out a Democratic gain elsewhere.

State Rep. Rick Saccone (R), who lost against Lamb in March and was generally viewed as a weak candidate, is running in the Republican primary. Some prominent Republicans hope state Sen. Guy Reschenthaler will win the primary instead of Saccone. Four Democrats are vying for their party’s nomination, with emergency physician Bob Solomon putting more than $100,000 of his own money into the race.

Pennsylvania’s 8th District: Then there’s the northwestern district represented by Democratic Rep. Matt Cartwright. This is a district Trump won by nearly 10 points, making it a major Republican pickup opportunity. Wealthy self-funder John Chrin hopes to win the GOP nomination there, even though he doesn’t actually live in the district anymore under the new map. Former prison guard Robert Kuniegel and former policeman Joe Peters are also running on the Republican side.