The Senate Majority PAC is a prominent super PAC dedicated to supporting Democratic candidates for the U.S. Senate through independent expenditures, such as advertising and other campaign activities. Founded in 2010 by a group of experienced Democratic strategists—including former aides to Sen. Harry Reid like Rebecca Lambe and Susan McCue, as well as Craig Varoga from Patriot Majority PAC, J.B. Poersch, Jim Jordan, Monica Dixon, and attorney Marc Elias—the organization was initially named Commonsense Ten. It rebranded as Senate Majority PAC in 2011 in response to the Citizens United Supreme Court decision, which enabled unlimited spending by outside groups. The PAC's mission is to protect and expand Democratic majorities in the Senate by countering Republican-aligned super PACs with aggressive fundraising and spending on behalf of Democratic incumbents and challengers. It has been closely aligned with Senate Democratic leadership, including former Majority Leader Harry Reid and current Majority Leader Chuck Schumer, and plays a key role in defending vulnerable seats during election cycles. Since its inception, the Senate Majority PAC has raised and spent hundreds of millions of dollars across multiple election cycles. In the 2012 cycle, it expended $42 million to support President Barack Obama's re-election and defend 23 Democratic Senate seats. In 2016, it received a donation of $250,000. More recently, in the first quarter of 2024, it raised $39.3 million, surpassing its Republican counterpart, the Senate Leadership Fund, and ended the period with $92 million in cash on hand. Major funding sources include nonprofit affiliates like Majority Forward, which contributed tens of millions in 2023-2024, and individual donors such as David Bonderman. The PAC discloses donors partially and has not reported federal lobbying activities. It coordinates with other Democratic groups like Women Vote! and Last Best Place PAC for targeted spending, primarily on independent expenditures totaling over $311 million in recent cycles. The organization operates from Washington, D.C., and maintains an active presence through its website and social media to mobilize support for Democratic Senate candidates.