Even Romney is pretending to be more conservative than Santorum:

Romney on Friday accused Santorum of expanding government during his two terms as a congressman and two terms as a senator.

“I hope that people take a very close look at his record because he was in Congress for about 20 years and during that time the size of the federal government doubled,” Romney said.

“And, by the way, he voted to raise the debt ceiling five different times without compensating cuts,” Romney added. He said Santorum voted for “billions of dollars in earmarks.”
\kansascity.com