The GOP presidential field still has no clear front runner, but the latest polls show Herman Cain joining former Massachusetts Gov. Mitt Romney and Texas Gov. Rick Perry in the top tier.

Cain's meteoric rise has sparked new scrutiny of his campaign ideas such as his 999 Plan, a proposal that would replace the current complicated income tax system.
      
The former Godfather Pizza CEO said he's not just "a flavor of the week" and that his recent climb in the polls will last because of the substance of his ideas.

"The 999 is catching on," Cain said. "The fact that I've described the illegal immigration problem as four problems is catching on." 

"The fact that we need to restructure Social Security, we can't keep just raising taxes and reducing benefits," he added. "The fact that I've talked specifically about how I would approach foreign policy."
   
On Sunday, Cain conceded that his signature 999 tax plan would raise taxes for some middle class Americans. 
 
The business man is by no means the only front-runner. Many believe Perry may prove to be the comeback kid.

Despite recent missteps, his latest fundraising news is good. Perry is the top GOP fundraiser, raking in $17 million -- $3 million more than Romney.

"He has a lot of resources, and he, in his career, has shown a penchant for going hard after his opponents," Obama campaign advisor David Axelrod said.
   
Cain raised less than Rep. Michele Bachman, R-Minn., but he said that's changing.

"Within the last two weeks, we've raised $2 million," Cain said. "So in other words, our fundraising is now beginning to pick up."
   
Meanwhile, reports filed late Friday show President Obama has raised more than $42 million through his campaign alone. The total for the GOP candidates is $52 million.