The National Republican Senatorial Committee (NRSC) is the official Republican Party committee and a political action committee dedicated to electing and supporting Republican candidates for the United States Senate. As one of the party's three national campaign committees—alongside the Republican National Committee (RNC) and the National Republican Congressional Committee (NRCC)—the NRSC focuses exclusively on Senate races, providing financial support, strategic assistance, research, and voter outreach to strengthen the Republican Senate majority. It operates as a fundraising and spending arm, raising funds from individual donors, PACs, party affiliates, and heavily relying on conservative donors to finance campaigns, ads, and ground operations in key battleground states. The committee plays a pivotal role in coordinating national Republican efforts during election cycles, particularly in competitive races that determine Senate control.

Founded in 1916 as the Republican Senatorial Campaign Committee following the ratification of the 17th Amendment, which established direct election of senators, the NRSC was reorganized and renamed in 1948 to its current form. It has evolved significantly since the 1976 Supreme Court decision in Buckley v. Valeo, which shaped modern campaign finance laws, allowing it to operate as a 527 political organization. Leadership is provided by a chair elected from Republican senators, with Tim Scott of South Carolina serving in that role since 2025, supported by vice chairs including Katie Britt (AL), Marsha Blackburn (TN), Bernie Moreno (OH), and Jim Banks (IN). Headquartered in Washington, D.C., the NRSC maintains close ties to the Senate Republican Conference and has a history of influential chairs such as Mitch McConnell (2007–2025) and John Thune (2025–present in related roles).

The NRSC's activities extend beyond elections to include policy advocacy and party-building initiatives, such as voter registration drives and digital campaigning. It has been involved in numerous high-stakes Senate battles, contributing to Republican gains or defenses in cycles like 2010, 2014, and 2020. Financially, it reports significant fundraising totals, often in the hundreds of millions per cycle, fueled by major donors to support its operations. While praised by supporters for bolstering conservative representation, the NRSC has faced criticism for its role in partisan spending and influence from large donors.