The wealthy West Virginia senator cut a personal check for $250,000 to Senate Majority PAC, the super PAC focused on defending Democrats’ majority this fall, according to first-quarter campaign finance reportsfiled this week. Although he’s the only senator so far this cycle to contribute to the super PAC from his personal accounts, his colleagues also are pitching in through their leadership PACs.

Senate Majority Leader Harry Reid (D-Nev.) and Sens. Barbara Boxer (D-Calif.) and Tim Kaine (D-Va.) have together given an additional $200,000 to Senate Majority PAC — which was co-founded by Reid’s former chief of staff Susan McCue — in the 2014 election cycle. The donations from Reid and Kaine were in the first quarter of 2014, while Boxer donated last year.

The contributions from the four senators highlights the balancing act the party must play this year while being outgunned by GOP outside groups such as Americans for Prosperity, which has dumped millions on battleground states in an effort to oust incumbent Democratic Sens. Mark Pryor of Arkansas, Kay Hagan of North Carolina, Mary Landrieu of Louisiana and Mark Begich of Alaska.

Democrats continue to openly question the growing role of money in politics and bash the AFP-backing billionaire Koch brothers on the Senate floor, but they need a strong performance this year from Senate Majority PAC to counter the conservative group’s attacks.

The powerful organization has raised nearly $20 million this election cycle, with donations from Reid, Boxer, Kaine and Rockefeller on campaign finance documents alongside wealthy Senate Majority PAC benefactors such as filmmaker Steven Spielberg, former New York City Mayor Michael Bloomberg and James Simons, a billionaire who gave the PAC $2 million in March.

And that money is going out the door into the burgeoning ad war by the millions: The super PAC has spent more than $11 million in defense of the Senate so far this election cycle and had more than $8 million on hand at the start of April.

The group is opposing top targets such as Rep. Tom Cotton in Arkansas, Senate Minority Leader Mitch McConnell in Kentucky, Rep. Cory Gardner in Colorado, Rep. Bill Cassidy in Louisiana, Terri Lynn Land in Michigan and Thom Tillis in North Carolina.

The super PAC has also spent money in support of Hagan and Rep. Bruce Braley, who is running for Senate in Iowa, and funneled nearly $500,000 to a pro-Begich PAC this year. Rockefeller might be a bit disappointed, though: None of his money has yet gone to West Virginia’s Senate race between Democrat Natalie Tennant and GOP Rep. Shelley Moore Capito.

The group will get another big boost before the November election, with President Barack Obama slated to attend a fundraiser for the super PAC later this year.