04/22/2012 03:35 EDT | Updated 06/22/2012 05:12 EDT

Rubio? Christie? Bush? Speculation about Romney's running mate in full throttle

WASHINGTON - Speculation about Mitt Romney's running mate is at fever pitch in the U.S. capital now that the former Massachusetts governor is all but assured the Republican presidential nomination.

In the corridors of power on Capitol Hill, at swank Georgetown dinner parties, in K Street bars and on the talk-show circuit, it's the subject of intense debate: Will it be Condoleezza Rice? Marco Rubio? Jeb Bush? Paul Ryan? Chris Christie?

Rubio, the Cuban-American U.S. senator from Florida, did little to silence the buzz surrounding his name on Sunday when he appeared on CNN's "State of the Union."

After denying for months that he has any interest in the job, Rubio didn't rule it out. He also touted a proposed immigration policy aimed at appealing to a large segment of the population who prefer U.S. President Barack Obama by almost 40 percentage points: Hispanics.

"I'm not going to discuss it anymore because now there's a real process in place... he has a process and we should respect that process," Rubio said with a smile when asked if he'd be interested in the job.

He agreed those comments would likely fuel even further speculation that he has the inside track.

"I think it's fair. I think the fairness in it is he has a real process in place... the last thing he needs is those of us in the peanut gallery to be saying what we would or would not do," said Rubio, who will appear with Romney on Monday in Pennsylvania ahead of the state primary.

Rubio said he hopes to see the Republican party become "the pro-legal immigration party" with the so-called Republican DREAM Act he's formulating. The initiative would allow some illegal immigrants who came to the U.S. as children to get permanent residency if they graduate college or join the military.

Romney, who campaigned bitterly against the current DREAM Act during primary season, recently said he might be open to the Republican version although the differences between the two are minor. The party's far-right conservatives have reacted in alarm, saying Romney will be reviled and distrusted if he signs on.

Rubio staked far more compassionate ground on Sunday in talking points certain to capture the attention of America's Hispanic community, the fastest growing demographic in the country.

"We have to make very clear that we support legal immigration," he said.

"It starts by recognizing that the vast majority of people who are here illegally didn't come here to steal from the American government. They are here in search of opportunity, they are doing what most people would do if their children were hungry and their family was suffering."

Romney has tapped a longtime aide, Beth Myers, to oversee his search for a running mate. He says he hopes to name someone before the Republican National Convention in Tampa in late August.

A smart pick, pundits say, would help him bridge gaps with Obama that are poised to cause him problems in the general election.

Romney struggles not just with Hispanics, but with women. Female voters make up almost 53 per cent of the American electorate, and polls suggest they prefer Obama by almost 20 percentage points.

Enter Condi Rice, former president George W. Bush's one-time secretary of state.

A recent CNN/ORC International survey had Rice on top of all other potential running mates, with 26 per cent of Republicans and Republican-leaning independents saying she'd be the best pick.

Rice, for her part, has said she has no interest in the job, but some have pointed out those sorts of denials often evaporate once potential running mates actually get the call from a presidential hopeful.

Jeb Bush's name is another that pops up frequently — often thanks to Rubio. On Sunday, Rubio said once again that George W. Bush's younger brother, a former Florida governor, would be "a fantastic vice president."

Bush, on the other hand, has frequently touted Rubio. And as recently as Friday, he attempted to tamp down any notion he'd be on the Romney ticket.

"I am not going to be the veep nominee .… Lay that to rest," he told Bloomberg.

Ryan, a Wisconsin congressman, is the potential running mate favoured by fiscal conservatives. He's a fiscal hawk from a pivotal swing state whose gravitas on budget issues is respected on both sides of the aisle on Capitol Hill.

"A Romney-Ryan ticket is the Democrats' worst nightmare, and it is our best shot at restoring the American dream," Jeffrey Kuhner, the Canadian-born president of the conservative Edmund Burke Institute, wrote recently in the Washington Times.

A recent poll out from Public Policy Polling, however, hints at the challenges for the Romney campaign as they determine who's got the right stuff. The survey has Obama currently leading Romney by three points at 49 per cent to Romney's 46.

According to the poll, four potential running mates would bolster Romney's numbers against Obama — Bush, New Jersey Gov. Chris Christie and former Republican presidential hopefuls Mike Huckabee and Rick Santorum.

Christie does the best in the survey, allowing him to achieve a 47-47 tie with Obama. The governor, considered a moderate on some social issues, has said he'd be open to discussing the job with Romney.

The poll suggests four others, however, would hurt Romney's numbers: Rubio, Ryan, Sarah Palin and Ron Paul, who remains in the race for the Republican nomination.

Palin, whose stint as John McCain's running mate four years ago caused a firestorm of embarrassment for his campaign, would cause the most damage. The one-time Alaska governor would prompt Romney to fall seven percentage points behind Obama, at 43 per cent to the president's 50.