The four remaining Republican contenders for the U.S. presidential nomination have faced off for the first time since January in a nationally televised debate.

The debate in Arizona Wednesday night came at a crucial phase in the nomination process, with former Pennsylvania senator Rick Santorum and former Massachusetts governor Mitt Romney in a close race for first place.

The two immediately locked horns over their records on government spending. Romney said Santorum had voted five times to increase the maximum debt the U.S. could have, a point he has repeated on the campaign trail.

Santorum countered that Romney had said he supported a debt ceiling increase last summer and wanted to raise taxes on the top one percent of U.S. earners, which Romney denied.

Texas Representative Ron Paul joined the fray, repeating a comment that Santorum was a “fake” conservative, professing one belief while campaigning, governing differently once in office, and then pledging later to repeal programs he had supported.

The attacks on Santorum's record highlight his growing importance in the nomination race. A nationwide poll released Wednesday by Quinnipiac University showed Santorum is surging ahead, leading Romney by 9 percentage points.

And while Romney performed strongly in early contests, Santorum has placed first in several recent state votes.

On the other hand, polls find Santorum would lose to Democratic President Barack Obama in the general election, while an Obama-Romney race would be too close to call.

Political analysts say Wednesday night's debate – which also featured former House Speaker Newt Gingrich – could leave a strong impression on voters in Arizona and Michigan, which hold primaries next week.

On March 6, voters in 10 states head to the polls to choose a challenger to take on President Obama in November's general election. The day is known as “Super Tuesday.”