The Senate Tea Party Caucus was an informal group of conservative United States Senators established on January 27, 2011, to promote the principles of the Tea Party movement, emphasizing fiscal conservatism, debt reduction, limited government intervention, and stronger immigration controls. Originating from the broader Tea Party movement that emerged in 2009, the caucus was initiated by Senator Rand Paul (R-KY) during his 2010 Senate campaign. Its founding members included Senators Jim DeMint (R-SC), Mike Lee (R-UT), Rand Paul, and Jerry Moran (R-KS). Unlike the more structured House Tea Party Caucus founded by Representative Michele Bachmann in July 2010, the Senate version remained small and informal, lacking institutional support, and aimed to coordinate Tea Party activists' efforts in the upper chamber of Congress.

The caucus's activities focused on advocating for a conservative agenda, including organizing events like press conferences and rallies to pressure for deficit reduction and oppose government spending. Its first public event was a gathering on the Capitol grounds shortly after formation. Despite enthusiasm from a core group of members, the caucus struggled with recruitment due to the Senate's institutional dynamics and skepticism from some Tea Party activists who viewed it as a Republican Party establishment effort. By 2012, it had not expanded significantly beyond its founding members, and reports indicated limited coordination with the defunct House caucus.

The Senate Tea Party Caucus played a role in amplifying Tea Party voices in legislative debates, such as voting against foreign aid to certain countries and pushing for conservative policies. However, its impact was constrained by its small size—often described as fitting 'in the backseat of a cab'—and it appears to have become inactive or dissolved in subsequent years, with no major activities reported after the early 2010s. It exemplified the grassroots conservative push within the Republican Party but highlighted challenges in translating populist energy into Senate-level organization.