Given the victories in 2010 of Tea Party-backed candidates, some observers were quick to claim that the movement had brought sweeping change to the political landscape in America. But the precise numerical effect of the Tea Party in terms of votes for candidates bears closer scrutiny.

A 2011 study by Brigham Young University published in PS: Political Science & Politics, “Tea Time in America? The Impact of the Tea Party Movement on the 2010 Midterm Elections” compiled and analyzed data on individuals, organizations and candidates who endorsed (or were endorsed by) the Tea Party Movement in order to model the impact that the movement had on voting outcomes.

The study’s findings include:

• Within Republican primaries, candidates endorsed by the Tea Party Express group enjoyed 8 to 9 percentage points more of the vote share on average than candidates without an endorsement. Candidates who adopted the Tea Party label by signing the “Contract for America” garnered a 20 percentage point increase or more on average in the Republican primaries.
• In the general election, however, Tea Party endorsements generally had little statistically significant impact on the vote. The exception was the FreedomWorks group, whose endorsement was associated with 2% more of the vote than that of non-endorsed Republican candidates. FreedomWorks was also one of the only Tea Party groups to give money to candidates.
• One theme of the 2010 election was the tension the Tea Party created within the Republican Party because of the energy it gave to outside or non-establishment candidates. 49% of independent candidates identified themselves as active Tea Party supporters, while 43% of “strong Republicans” were actively supportive of the Tea Party Movement. Only 26% of “not so strong” Republicans identified with the Tea Party.

The researchers conclude that “the endorsement strategies of the movement in general elections did not produce dramatic results. However, strategies targeted to those conditions most favorable to the movement did occasionally have an impact, as demonstrated by the case of FreedomWorks. Endorsements had a larger impact in the primaries.”