Santorum scoffs at poll showing him losing ground in Pennsylvania

UPDATED 4:19 p.m. ET

(CBS News) APPLETON, Wis. - If there's any doubt in Rick Santorum's mind about the Pennsylvania primary, he's not showing it.

When asked about how he will survive a string of primaries in largely unfriendly Northeastern states, Santorum has pointed to his home state. And on Monday, he pushed back against a recent poll by Franklin & Marshall College that shows him with only a narrow, two-point lead over rival Mitt Romney.

"There's one poll that's ridiculous," Santorum said of the Franklin & Marshall survey, which showed him ahead, 30 percent to 28 percent, compared to February when he led 45 to 16 percent. "The other polls that have been out show us 15 to 20 points ahead, and we feel pretty comfortable that's where we are."

Santorum will spend the Wisconsin election night in Pittsburgh -- his second campaign night in Pennsylvania -- and he plans to begin campaigning there on Wednesday ahead of the state's April 24 primary.

With the month ahead -- which includes primaries in Delaware, Connecticut, New York, and Rhode Island -- appearing to favor Romney, Santorum is openly gunning for an open convention in August.

"I think it would be a fascinating display of open democracy, and I think it would be an energizing thing for our party to have a candidate emerge ... who isn't the blessed candidate of the Republican establishment. I think that's a good thing, it's a good narrative for us," Santorum told reporters as he toured a Simon's Specialty Cheese store in Appleton.

In a new line of attack for Santorum, he draw a contrast with Romney on Second Amendment issues. During a speech later on Monday to a crowd of about 200 in Menasha, Wis., the former senator referred to himself as someone who countered efforts in 1990s to increase gun control. That differentiated him, he said, from "another candidate in this race who is a former governor of Massachusetts who will go nameless."

"I didn't support the Brady Bill when he did," Santorum said, referring to a 1993 law that instituted federal background checks on people purchasing guns. "I didn't support the assault weapons ban. I stood tall and I didn't say that we have a lot of good gun law in Massachusetts and I won't touch any of them. I didn't put taxes on gun registration and ownership, increase it by 400 percent."

Santorum has stepped up attacks on Romney in his last two days of campaigning in Wisconsin and is still only lukewarm about promising to support him if he is the eventual nominee.

"A moderate Massachusetts governor is not going to make that strong contrast. He'll pull out the Etch a Sketch," he said.

And while he did promise to back Romney if his rival becomes the nominee, he added: "But it's so much harder to win when you aren't motivating the people that you need to in this country to get out and vote."