Republican Debate: It was a 'Surging Santorum vs. Raving Romney' Show [PHOTOS]

The Arizona CNN Republican debate, perhaps the last in the roller-coaster campaign to challenge President Barack Obama, saw rivals piling criticism on Rick Santorum, who was apparently trying to build on his surprise rise in recent polls.

The CNN-sponsored debate was held in the southwestern state of Arizona six days before crucial votes there and in Michigan, which is the former Massachusetts governor Mitt Romney's home state. Romney won in the industrial state when he ran in 2008 and had been expecting yet another win there.

However, it's former Pennsylvania senator Santorum who has emerged as his leading challenger in the Republican presidential race, and to halt Santorum's surge, Romney appeared to be more aggressive while clashing with Santorum over the federal government's power.

Romney joined forces with libertarian Congressman Ron Paul, who questioned Santorum's conservative credentials. When asked why his campaign had run a television ad calling Santorum a fake, Paul replied candidly: Because he's a fake.

Santorum saw a surprise surge in his candidacy in the last weeks after he won three contests on the same day. On the other hand, Romney still faces skepticism among conservatives who detest his shifting stances on key issues.

Given that, all eyes are now on Santorum's battle with long-term frontrunner Romney on Feb. 28 in the Michigan and Arizona primaries, setting the stage for the crucial March 6 Super Tuesday contest, when 10 states will vote.

Santorum was the debate's aggressor on federal bailouts, who said by going against the bailouts, he took a firm stand, but with Romney, it was not the case.

With respect to Governor Romney that was not the case, he supported the folks on Wall Street and bailed out Wall Street - was all for it - and when it came to the auto workers and the folks in Detroit, he said no, Santorum said. That to me is not a principled consistent position.

General Motors and Chrysler have recovered after taking huge bailouts, and that forced Romney to explain a 2008 editorial, to which he gave a provocative headline: Let Detroit Go Bankrupt.

Romney, too, went after his chief rival repeatedly. He retaliated by saying Santorum voted to lift the debt ceiling and supported earmarks, the much-ridiculed pet spending projects that members of Congress often slip into appropriations legislation, Reuters reported.

According to Romney, Santorum had supported a much-derided $400 million bridge to nowhere project in Alaska that was eventually abandoned.

To that, Santorum replied saying Romney had sought earmarks to pay for security at the 2002 Winter Olympics in Salt Lake City.

The back-biting between Santorum and Romney was so fierce that at one point the two candidates talked over each other, refusing to cede the floor. While the crowd booed many times, debate moderator John King of CNN repeatedly let the two candidates battle it out.

Below are some of the intense moments from the Wednesday's testy debate. Feel the heat!