DAVENPORT, Iowa - For the first time in this race, Rick Santorum finds himself getting not only noticed by the other candidates, but on the receiving end of attacks.

Rick Perry released a radio ad Thursday hitting Santorum for earmarks he supported while he was in Congress. On Thursday evening Santorum responded, telling reporters after his event that "it's been sort of difficult to go through this race and not get punched."

While his opponents - especially Newt Gingrich - have been under assault via television and radio ads, as well as mailers here, Santorum has been able to fly under the radar. But now that a CNN/Time poll released Wednesday put him at third place in the race behind Mitt Romney and Ron Paul, he's fair game.

Thursday evening Santorum held a town hall at a senior center in Davenport to an enthusiastic crowd of over three hundred, speaking and answering questions for almost two hours.

After his event at the Center for Active Seniors, Santorum said in previous races he's been "beaten, bloodied, bruised" - a big difference from this cycle.

"I say it all the time, I don't have a perfect record, but I have a pretty darn good one and the reasons I did what I did, if I made a mistake I admit it, but if I think I did the right thing, I'm going to stand up and fight for the things I believe in," he said.

He defended some of the past earmarks he requested and supported, which includes Alaska's infamous "Bridge to Nowhere," against the Texas governor's criticism.

"I'm not too sure that earmarking funds, when Rick Perry hired people to earmark funds for Texas, is necessarily a great shot by Rick Perry. And every Congressman in the state of Iowa did the same thing. Every senator earmarked funds, and this is something that the state of Iowa understands is - was done and has been done for a long time.  And subsequent to my being in the Senate was found to be abusive and was ended," Santorum said. "So, I don't - if this is the best they got against me, they better go back to the drawing board."

This evening's event was possibly the biggest crowd Santorum has had at an event while he's been barnstorming the state for months.

Thursday afternoon Rick Perry, Santorum's most head-on opponent at this point, admitted to not knowing about the Supreme Court case Lawrence v. Texas, a case which struck down the state's anti-sodomy law, and similar laws in 13 other states.

A potential caucusgoer asked Perry to defend his criticism of limited government in the case. Perry said he wasn't familiar with it, calling it a "gotcha question."

"I wish I could tell you I knew every Supreme Court case. I don't, I'm not even going to try to go through every Supreme Court case, that would be - I'm not a lawyer," Perry said.

In 2003, the Supreme Court ruled Texas' anti-sodomy law to be unconstitutional in a 6-3 ruling in Lawrence v. Texas, and the case nullified anti-sodomy laws in 13 other states at the same time. Perry, an opponent of gay marriage and the ability of homosexuals to serve openly in the military, served as governor when this case was decided.

"This was a foundational case that established rights that the marriage movement - the gay marriage movement used to get courts to impose gay marriage, and whether it's a gotcha question or not, I think good preparation is a very important thing for a president to have when you are entering into the battle," Santorum said.

ABC News' Arlette Saenz contributed to this report.