"She's got a record of misstating and making false statements," Pawlenty said.
Bachmann, who has risen in polls since entering the race this summer and has eclipsed Pawlenty, quickly responded with a list of what she called Pawlenty's liberal policies when he was Minnesota's governor, including his support for legislation to curb industrial emissions.
"You said the era of small government is over," she told Pawlenty. "That sounds a lot like Barack Obama if you ask me."
Each seeks to become the main challenger to Republican front-runner Mitt Romney, who isn't officially participating in Saturday's Ames Straw Poll. The Iowa tradition is considered a key early test.
For Pawlenty, the straw poll is a make-or-break moment to show he can compete. For Bachmann, it's a chance to keep up her momentum going in a key early state.
In the two-hour debate, the squabbling by Pawlenty and Bachmann allowed Romney to remain above the fray and emerge relatively unscathed by his rivals.
Much of the rest of the debate was heavily focused on the president, with Romney and his seven rivals each seeking to prove he or she was the strongest Republican to take on the Democratic imcumbent.
"Our president simply doesn't understand how to lead and how to grow the economy," Romney said. He also criticized Obama on the downgrade of the nation's credit rating.
The Associated Press contributed to this report.