Democrats have been plotting against Toomey for nearly two years; in recent months, they’ve targeted him for, essentially, being too Republican, and for opposing the nomination of Merrick Garland to the U.S. Supreme Court. But their fortunes have looked more promising since Donald Trump took the lead in the presidential race. Pennsylvania is a swing state, but has gone blue in six of the last seven presidential elections. While Trump is leading Ted Cruz and John Kasich by wide margins there, he is not expected to wow among the state’s more moderate voters if he’s the nominee. Instead, his candidacy is expected to negatively affect down-ballot Republicans like Toomey in the general.

November’s contest gets started Tuesday night when polls close, and national Democrats, including President Obama, want McGinty to be the victor. She’s never held elected office, but has long been part of the Democratic political scene. Before working for Wolf, she ran against him in the 2014 gubernatorial primary race. Before that, she led the state Department of Environmental Protection. And before that, she worked on Al Gore’s presidential campaign and as chair of the White House Council on Environmental Quality.

She’s wracked up endorsements in the last few months, including from Senator Majority Leader Harry Reid; unions like the SEIU; the Democratic Senatorial Campaign Committee; and the pro-choice women’s group EMILY’s List. Obama and Vice President Joe Biden publicly backed her in late March, “another sign,” The Hill wrote, “that the party’s establishment is coalescing behind her in a contentious Pennsylvania primary battle.”

The endorsements have been glowing—as endorsements typically are—citing her career in public service. But there’s political calculation going on as well. Biden has taken a particular interest in Pennsylvania as part of his boots-on-the-ground effort to flip the Senate; he’s campaigned with McGinty in the past and was in Philadelphia with her on Monday. Pennsylvania Democrat Bob Casey has said she’s the party’s best chance. “I think she will be the strongest nominee in the fall election against Senator Toomey,” he said. “And that’s part of the determination that I have to make as a Democratic leader in the state but also as a voter.”

Sestak, for his part, seems proud not to have establishment backing, much like Bernie Sanders has rejected its support of Hillary Clinton. This isn’t the first time he hasn’t gotten it. Sestak, a former Navy admiral who represented the Philly ‘burbs in Congress, hasn’t always colored between the Democratic Party’s lines. Against party wishes, he challenged Senator Arlen Specter in the 2010 Senate primary, but lost to Toomey in the general. This cycle, he didn’t even give the DSCC a heads-up that he was announcing his campaign, which kicked off with Sestak planning to walk the width of Pennsylvania.