CORALVILLE, Iowa — Fighting back against the charge he’s too conservative to be the Republican presidential nominee, former Sen. Rick Santorum told Iowa voters Thursday he isn’t going to walk back any of his conservative stances just to get elected, and even embraced his reputation as a rabble-rouser in his dozen years in the Senate.

After an event in Coralville, Iowa, the surging presidential candidate said he was not afraid to “throw the bombs that are needing to be thrown, when bombs need to be thrown.”

Call it Santorum-entum: Mr. Santorum has seen his standing in the polls rise, with a CNN survey on Wednesday putting him in third place with 16 percent of the vote. With the jump in polls, he’s also seeing more scrutiny both from voters and from the press.

In an interview on NBC on Thursday morning he defended his personal belief, as taught by his Catholic faith, that contraception is morally wrong, but said he wouldn’t try to outlaw it the way he supports outlawing abortions.

“That’s a fundamentally different thing than taking a human life,” he told NBC. “That’s something I don’t believe is right. But there’s a lot of things that I don’t believe are right that the government shouldn’t be outlawing. Those are moral decisions that fall outside of the law”...