Republican presidential candidate Rick Perry said on Wednesday he will propose a flat tax as part of an overhaul of the U.S. tax code as he seeks to claw his way back to the top tier of the 2012 race.

A day after a bruising debate with his rivals for his party's presidential nomination, the Texas governor told participants at a conference of Western Republicans that he will outline his economic growth package next week.

He has a speech planned for October 25 in South Carolina, the state where he first announced his candidacy in August and which holds an important early contest in the road to the Republican nomination.

"I want to make the tax code so simple that even Timothy Geithner can file his taxes on time," Perry said, referring to President Barack Obama's treasury secretary, who was famously late in filing tax returns.

Perry jumped into the front-runner position when he announced his candidacy two months ago. But a series of shaky debates has left him trailing former Massachusetts Governor Mitt Romney and businessmanHerman Cain in the race to pick the Republican candidate who will challenge Democratic President Barack Obama in November 2012.

Perry exchanged sharp blows with Romney at the CNN-sponsored debate in Las Vegas on Tuesday night in an acrimonious exchange over illegal immigration that generated front-page headlines and photographs.

Without mentioning Romney by name, Perry told the Western Republicans that he was not the establishment candidate, but was a true conservative. The Texan wants to re-establish himself as the alternative to Romney -- a distinction that, at least temporarily, has been filled by Cain.

'Unbridled truth'

Perry ridiculed U.S. news organizations that have declared that Romney looks to be the eventual nominee, saying, "Primary voters and caucus voters haven't gotten that memo yet."

"You will not hear a lot of shape-shifting nuance from me," he said. "I'm going give the American people a huge helping of unbridled truth."

At the debate, Perry criticized Cain's proposal for a 9-9-9 tax reform overhaul that many Republicans have found appealing. It would limit personal and corporate income taxes to 9 percent while creating a 9 percent national sales tax.

In his Wednesday speech, Perry said he would scrap the "3 million words of the tax code, starting over with something simpler, a flat tax," and end lawmakers' ability to attach individual spending projects -- known as earmarks -- to appropriations bills.

Perry said he also would propose an amendment to the U.S. Constitution to require that the federal budget always be balanced. This has been a long-time goal of conservatives but hard to accomplish because it would require congressional passage and ratification by two-thirds of the states.

"I will barnstorm this country from Day One by going to all 50 states if that's required for a balanced-budget amendment," he said.