The former Pennsylvania senator will be a harder target for Mitt Romney's attack machine. But there's plenty of fodder their if he wishes to use it.

SFGate:

Mitt Romney took aim at the rival who beat him in three Republican presidential contests in one day, berating Rick Santorum as a long-time Washington insider and lumping him with Newt Gingrich.

Romney, whose status as the frontrunner in the Republican was shaken by the Feb. 7 results, yesterday compared both Santorum and Gingrich with President Barack Obama, saying all three lacked experience in the "real economy."

Santorum, a former senator from Pennsylvania, and Gingrich, the former U.S. House speaker, "spent a lot of time in Washington and during that time they spent a lot more money than they took in," Romney said in Atlanta, Georgia.

Romney, who has stressed his experience as a private equity executive, went on the offensive after Santorum revived his candidacy with wins in Missouri's non-binding primary and caucuses in Minnesota and Colorado.

The Romney attacks are set to continue today. His campaign has scheduled a conference call for reporters in which two Oklahoma state officials are to target Santorum's "support of reckless spending" and "enthusiastic defense of earmarks," according to a statement.

There are a lot of Republicans who remember Santorum's flippant remarks about earmarks during the height of the battle to ban them from congress. That would appear to be a more productive line of attack than criticizing Santorum for not having experience in running a business. Santorum's legendary pork procuring skills for Pennsylvania will no doubt come up for scrutiny.

Romney will probably husband his resources for a few days as the next primaries aren't until February 28 in Michigan and Arizona. He will also continue to build organizations in Super Tuesday states where he aims for a knockout blow against Gingrich.