WASHINGTON — A new national poll shows Rick Santorum with a nine-point lead over Mitt Romney among Republican voters heading into Wednesday night’s Republican primary debate in Arizona.

Romney and Santorum remain in a near dead heat with President Barack Obama, who barely edges them out in a general election match-up, according to the survey released Wednesday by the Quinnipiac Polling Institute. Romney is slightly closer than Santorum when paired against the incumbent president, lagging only two points behind Obama.

In the GOP field, Newt Gingrich and Ron Paul trail the frontrunners with with 14 percent and 11 percent, respectively.

And in a hypothetical two-man race, Santorum’s lead polling lead widens, 50 percent to Romney’s 37 percent.

At a news conference Wednesday announcing the results, Quinnipiac Polling Institute Assistant Director Peter Brown called Santorum’s lead “solid but not dramatic.” Brown said he still sees Romney as the GOP frontrunner, mostly due to the former Massachusetts governor’s delegate tally.

“Leads, as we all know this year, have been somewhat ephemeral during campaigns,” Brown told reporters. “They’ve come and gone.”

In the national survey, 48 percent of GOP voters said it would be bad for their party if none of the current candidates win enough delegates to be nominated before the national convention in August. That could force a “brokered convention,” Brown said. If party leaders were to nominate someone not in the primary race, 32 percent prefer New Jersey Gov. Chris Christie, according to the poll.

Brown said the Quinnipiac poll confirms that voters want the primaries to pick their party’s nominee, not convention delegates.

He pointed to Santorum and Romney’s competitiveness in polling against Obama as evidence that a grueling primary season has not yet damaged the GOP brand.

“At this point, at least nationally, all the controversy in the Republican primary does not appear to be hurting the Republican vote as they look towards November,” Brown said.

The four candidates are set to take the stage Wednesday night for their first debate in almost a month at the Mesa Arts Center in Mesa, Ariz. The televised event comes five days before Arizona and Michigan’s primary contests, where Romney and Santorum have been rallying back and forth in state polling.

The Quinnipiac poll, the Hamden, Conn.-based institute’s first national gauge of the GOP primary season, was conducted from Feb. 14 to 20 and surveyed 2,605 registered voters. It has a 1.9 percent margin of error.