Eight declared candidates for the U.S. Republican Party's presidential nomination used a nationally televised debate Thursday to blast President Barack Obama's economic record, while also aiming their rhetoric at each other.

The debate at the Iowa State University in the city of Ames was staged ahead of a key straw poll, or test vote, at the Iowa State Fair that could identify which candidates have a legitimate chance to win next year's nomination.

One of the most memorable exchanges occurred between two candidates from Minnesota, former governor Tim Pawlenty and Representative Michele Bachmann. Pawlenty dismissed Bachmann's time in Congress, saying her “record of accomplishment and results is nonexistent.” Bachmann responded by calling Pawlenty's past support to limit carbon emissions and other measures as similar to that of Mr. Obama.

The other candidates participating in Thursday's debate were former Massachusetts governor Mitt Romney, the current front-runner in polls; former House speaker Newt Gingrich; Jon Huntsman, a former Utah governor and ex-U.S. ambassador to China; U.S. Representative Ron Paul; former Pennsylvania senator Rick Santorum; and restaurant executive Herman Cain.

The debate was overshadowed by the news that Texas Governor Rick Perry will formally enter the race for the nomination on Saturday, the day of the Iowa Straw Poll. Perry has a strong record of job growth during his time in office, and can potentially appeal to both social and economic conservatives, making him a formidable candidate.

Perry is the longest-serving governor in Texas history. He took over from Republican George W. Bush after Mr. Bush won the 2000 U.S. presidential election.

Surveys found most Republican primary voters plan to support Romney, with Perry next in line.

Another potential candidate, former Alaska governor and 2008 vice presidential candidate Sarah Palin, did not participate in the debate.