Republican presidential candidates are gathering on the stage yet again Tuesday's tonight for another debate. 

Viewers who watch the debate on CNN at 8 p.m. Eastern time tonight may focus heavily on Herman Cain, who has emerged as a leader in the field of candidates after largely flying under the radar for much of the political process. Some political pundits see tonight's debate as Cain's chance to show that he's a serious candidate who could compete with President Barack Obama in the 2012 general election.

To demonstrate staying power, Cain has to add something new to his 9-9-9 plan. How will 9-9-9 help entrepreneurs? Working women? How will it renew the real-estate market? He needs his plan to grow so he can grow as a candidate, said GOP strategist and CNN contributor Alex Castellanos, according to CNN.com.

Cain's plan, which has drawn criticism, would initially scrap the current tax code and replace it with three flat taxes: a 9 percent personal income tax, a 9 percent corporate tax and a 9 percent national sales tax. Eventually, he would implement a single consumption, or fair tax. But the former pizza chain CEO has been skimpy with details on how his plan would work.

One candidate will be absent from the debate: Jon Huntsman, who's skipping the event to protest the Nevada GOP's decision to move their primary up to Jan. 14, throwing the entire primary schedule out of whack and threatening the New Hampshire Primary's first in the nation status. The Washington Post reported that instead of joining his rivals out West, Huntsman will host a town hall in New Hampshire, part of his decision to focus all of his energy on winning the Granite State.

CNN, which is hosting tonight's debate along with the Western Republican Leadership Conference, said the focus will be on economics and issues at the border. CNN said it'll host another debate next month in Washington, focusing on national security and foreign policy. That debate will be co-hosted with the Heritage Foundation and the American Enterprise Institute.