The former Pennsylvania senator leads former Massachusetts Governor Mitt Romney, 30 to 27-percent.
That three-percentage point difference is within the poll's margin of error.
Texas Congressman Ron Paul is third with 12-percent support and former House Speaker Newt Gingrich is fourth at 10-percent.
Santorum's support has nearly doubled since last month, while Romney's support is about the same.
Gingrich's support is less than half what it was in January.