Reporting live from the 12th District, there have definitely been some shenanigans playing out here in the Lee-Patel race, Geoffrey, so I'll be interested to see what happens with the other Squad challenges. For example, the 14th Ward Independent Democratic Club, an influential progressive group located on the East End in Pittsburgh, endorsed Patel over Lee. In 2022, the IDC endorsed Lee over the more moderate Steve Irwin, so it may look like the club has had a change of heart.

However, there's much more happening behind the scenes. Allegheny County's 14th Ward includes Squirrel Hill, traditionally the home of Pittsburgh's orthodox Jewish community. In January of this year, over 150 new members became a part of the IDC in advance of their annual votes on board members and endorsements, growing the club's membership by more than 50 percent. The new IDC members ousted board members that they considered too pro-Palestine, and were instrumental in directing the group's endorsements. So while it may appear to voters that a progressive group is abandoning Lee, a peek behind the curtain reveals quite a bit more is going on.

—Mary Radcliffe, 538

In the Pittsburgh-based 12th District, progressive Rep. Summer Lee could be vulnerable against Edgewood Borough Council member Bhavini Patel in the Democratic primary. Two years ago, in her first bid for this seat, Lee only won her primary by less than a point. And Patel's challenge has turned into a referendum on Lee's party bona fides. Behind this is Lee's membership in The Squad, a group of progressive House Democrats who've often been at odds with party leaders. This has been especially apparent in the intraparty debate over the Israel-Hamas conflict in Gaza, most recently demonstrated by The Squad joining with about one-sixth of House Democrats in voting against foreign aid to Israel.

Lee's critics have often portrayed her as more dogmatic than pragmatic, a theme Patel's campaign has played up by arguing that Lee wants to undermine Biden and the Democratic Party. She has run ads attacking Lee for opposing the Biden administration and criticized Lee's support for the "uncommitted" movement in the presidential primary that wants Biden to adopt a less pro-Israel stance. Lee has countered by emphasizing her ability to bring federal investment to the district and her pro-choice record. Her campaign has also criticized "Republican-funded super PACs" for meddling — a reference to Patel's backing from Moderate PAC, a group mostly funded by a GOP donor, and the potential influence of the bipartisan American Israel Public Affairs Committee, which has said it might spend $100 million against progressives this cycle.

Heading into the primary, Lee probably has the upper hand. We have no polls, but Lee had outraised Patel nearly 4-to-1 ($2.3 million to $602,000) as of April 3. Meanwhile, outside spending has run about even, according to OpenSecrets. Surprisingly, though, AIPAC's super PAC has not spent money against Lee despite investing $3.9 million to stop her in the 2022 primary. That may mean that AIPAC thinks Patel can't win, that she already has sufficient support and/or that support associated with AIPAC could harm Patel more than help her.

—Geoffrey Skelley, 538

It'll still be a little while before full results start rolling in from Pennsylvania, and, in the meantime, allow me to suggest some easy listening. Yup, it's the 538 Politics podcast!

On Monday's episode we previewed a couple of tonight's races in Pennsylvania and talked about the state's significance come November. We also considered whether House Speaker Mike Johnson can last as something of a coalitional speaker, frequently relying on votes from Democrats to get legislation passed. And lastly, we tested our knowledge of what Americans think about climate change, according to the polls. Give it a listen!

—Galen Druke, 538

Happy primary day to those who celebrate! (That's us, fellow Pennsyvlanians.)

The Keystone State is already in the public eye this election cycle, as it's expected to be a battleground state for both the presidential race and a critical U.S. Senate race between incumbent Democratic Sen. Bob Casey and Republican David McCormick. And there are consequential races down the ballot, too: Several competitive U.S. House races could impact the balance of the House majority, while Democrats are hoping to compete for control of both chambers of the state legislature to earn their first state government trifecta in more than 30 years.

And while the candidates for president and Senate are set, today's primary contests will determine just who's on the ballot from each party in those key down ballot races. Tonight, we're closely tracking a handful of significant U.S. House races, including progressive Rep. Summer Lee's bid to hold off a more moderate challenger; moderate Republican Rep. Brian Fitzpatrick's challenge from the hard right; and a three-way GOP primary to decide who will face off against Rep. Susan Wild in one of the most competitive House races this fall. We've also got our eyes on some hotly contested primary contests for statewide offices like attorney general and a number of spicy state legislative races.

As usual, we'll be here to guide you through it all with the latest results and analysis throughout the evening. We should start seeing results come in shortly after polls close at 8 p.m. Eastern. Thanks for joining us!

—Tia Yang, 538

In Pennsylvania's 10th District, where several Democrats were in today’s primary, former evening news anchor Janelle Stelson is currently leading with 48 percent of the expected vote in. Stelson has backing from EMILY’s List, which is historically a good sign. According to our analysis of the 2022 primaries, 85 percent of candidates endorsed by EMILY’s List’s in open primaries won their races. Interestingly, three candidates in open primaries endorsed by EMILY's List in California did not advance to the general election, which will bring down their success rate. But we'll need to wait and see how EMILY's List candidates do overall this cycle.

—Meredith Conroy, 538 contributor