Former Senator Rick Santorum of Pennsylvania accused former Gov. Mitt Romney and former Gov. Jon Huntsman of “weakness” for choosing to not campaign aggressively in Iowa, The Hill reports.

"I think it's a big mistake for any candidate to bypass Iowa. It shows weakness, not strength,” said Santorum in reference to his two fellow GOP presidential candidates.

"If you can't compete in the heartland of America for heartland Republican voters, you're going to have a hard time not just winning the Republican primary, but you're going to have a hard time making the case that you can defeat Barack Obama, that you'll have the energy and enthusiasm behind you that a candidate needs to rally folks to win this election," he said. "So I think it's a big mistake for Gov. Romney, for Gov. Huntsman."

Romney and Huntsman have been focusing their attention on New Hampshire, another early primary state that can often have a major impact in the nomination process.

Former Governor Romney of Massachusetts still leads in Iowa according to the most recent poll by the Des Moines Register, but is steadily losing ground to his fellow candidates.