AMES, Iowa — No more Mr. Minnesota Nice Guy.

Former Gov. Tim Pawlenty assailed his GOP primary opponents at a presidential debate Thursday evening, directing most of his criticism at his chief Iowa competition, Rep. Michele Bachmann (R-Minn.), but saving some jabs for national frontrunner Mitt Romney.

“It’s an indisputable fact that in Congress, her record of accomplishment and results is nonexistent,” Pawlenty said. “And that’s not good enough for our candidate for president of the United States, and that’s not going to be good enough for the president of the United States to serve in that capacity.”

That remark was just one example of the new level of rough-and-tumble campaigning the GOP contenders are engaging in as voters start to indicate their preferences in contests that matter.

Pawlenty had the most at stake in the lead-up to the Ames straw poll Saturday. Polls show him lagging, while Bachmann has overshadowed Pawlenty’s Iowa-or-bust campaign in recent weeks. Many Iowa Republicans say he must place in the top three slots in the straw poll to ensure his campaign’s survival.

After he missed the opportunity at the previous debate to criticize Romney, it took Pawlenty just 15 minutes to make his move Thursday night.

Pawlenty quipped that he would cook dinner or mow the lawn of any debate watcher who could come up with President Barack Obama’s plan to save government entitlement programs. But he cautioned that in Romney’s case, he would only mow his first “acre” of grass — an insult to highlight the former Massachusetts governor’s large personal wealth.

Romney was visibly not amused with Pawlenty’s comment.

Bachmann was not so gentle in her responses to Pawlenty’s criticism.

“People are looking for a champion,” Bachmann said at the debate, sponsored by Fox News and the Washington Examiner. “They want someone who’s been fighting. When it came to health care, I brought tens of thousands of people to Washington to fight it.”

Pawlenty pointed out that the president’s health care overhaul is still law, saying, “If that’s your record of effective results, please stop, because you’re killing us.”

But some Republicans speculated that the biggest winner of the debate wasn’t even on the stage.

Several hours before the start of the debate, Texas Gov. Rick Perry announced he would seek the presidency. Most of the contenders in Iowa welcomed him to the race, but his candidacy casts a long shadow over the weekend festivities. Former U.S. Ambassador Jon Huntsman ribbed Perry’s recent prayer event, saying, “We all need prayers, and I hope he offers up a bunch for everyone up on this stage.”

Perry will skip the straw poll Saturday in favor of a trip to South Carolina and New Hampshire. He’ll head to Waterloo, Iowa, on Sunday. But straw poll attendees can write in Perry’s name, a wild card in a contest where Bachmann is the early favorite.

Former Alaska Gov. Sarah Palin, who has yet to clarify her intentions for 2012, will stop by the Iowa State Fair on Friday afternoon.

The candidates who did participate in the debate pleaded for more face time. Former Sen. Rick Santorum (R-Pa.) begged the hosts twice to give him equal treatment. Former Speaker Newt Gingrich complained about the moderators’ questions.

Rep. Ron Paul (R-Texas) also fought the clock, asking for more time to explain his position on Iran against a field of GOP candidates who mostly disagreed with him.

Huntsman, making his first debate appearance as a presidential candidate, acknowledged he stood apart from the crowd of Republicans onstage because of his support for civil unions and for Speaker John Boehner’s legislative deal to raise the debt ceiling.

“I know I’m a little bit different than everyone else in that regard,” Huntsman said of the Ohio Republican. “I thought Speaker Boehner should be complimented for what he did. This country should never default.”

Bachmann said that never increasing the debt limit would be part of her plan to turn the economy around, and Romney said he would only have supported a plan to cut and cap spending and a balanced budget amendment. He attempted to avoid a direct answer on whether he would have signed the deal, saying: “I’m not going to eat Barack Obama’s dog food. What he served up is not what I would have as president of the United States.”

Ahead of the debate, thousands of attendees lined up outside the auditorium on the grass, waiting to go through the security check. Guests adorned in everything from black leather motorcycle pants to formal business suits waited to get through a slow-moving line.

Santorum and Paul supporters were the most visible parties outside the debate hall. Santorum’s cadre of college student volunteers took over a cement walkway near the entrance, ringing a cowbell and playing a tambourine to show their support. A handful of people wore Romney T-shirts and stickers.

When a man dressed in white colonial garb carrying a silver teapot was forced to leave his full-sized flagpole behind, he griped, “I have to leave the rebellion outside.”