| ASTON, Pennsylvania
ASTON, Pennsylvania Popular Florida Senator Marco Rubio campaigned with Mitt Romney on Monday, increasing speculation that the conservative Cuban-American might be high on the Republican presidential front-runner's list of potential vice presidential running mates.
Rubio would bring a number of attributes to the ticket should Romney pick him. He could appeal to some Latinos, a large majority of whom back Democratic President Barack Obama, and he could inspire conservatives who worry Romney is too moderate.
But Romney, who said his search is in the "very early stages," will have to look hard at Rubio's inexperience on the national stage. The Tea Party favorite has been a U.S. senator for less than two years, making him an unlikely match for a role in which he may have to step into the presidency at any time.
Romney is running neck-and-neck with Obama in national opinion polls but needs to make up ground in several battleground states where the election is likely to be decided.
The former Massachusetts governor appeared side-by-side with Rubio at a news conference where Romney did most of the talking. They then held a town hall event and took turns answering questions from supporters.
Romney brushed off two questions from reporters whether Rubio was on his list for potential vice presidential picks, a process that will play out over the next four months ahead of the Republicans' August convention in Florida to nominate their candidate to face Obama in the November 6 election.
"The process for selecting a vice presidential running mate is just beginning," Romney said.
He noted that longtime aide Beth Myers has begun to put together a system for checking out possible nominees and reviewing tax returns and other background material, "but we really haven't had a discussion yet of putting together a list or evaluating various candidates."
RUBIO IS COY
Rubio, 40, has lately sounded coy about the idea of a vice presidential nod after ruling it out repeatedly in the past. Conservatives speak warmly of the idea and Romney advisers say he will be considered, but some Republicans voice worries he may simply be too young for the job.
Rubio, asked whether he had the experience necessary to serve as vice president, would not comment. "I'm not talking about that process any more," he said.
Obama leads Romney among Hispanic voters by a whopping 40 percentage points, putting pressure on Romney to take steps to reduce that margin and make himself more competitive in states where the Latino vote could be decisive, like New Mexico and Nevada.
Romney, the presumptive Republican presidential nominee now that his conservative challengers have fallen away, showed an eagerness to get on with the general election campaign against Obama in a battle he wants to keep on the sluggish U.S. economy.
Romney is expected to sweep five states that vote in primary elections on Tuesday to add to his delegate total on the way to the 1,144 needed for the nomination.
"I need your help on November 6," he told supporters earlier in South Park Township outside Pittsburgh. "Come join us in this effort."
One of the issues that will come up during the general election campaign is what to do about illegal immigrants after the failure by both parties to deal with the issue in recent years.
In Aston, Romney told reporters he planned to lay out a series of policy proposals - including unspecified adjustments to the U.S. visa program - aimed at addressing a sore point with the Hispanic community, the lack of a comprehensive immigration reform.
But he would not commit to Rubio's proposal for a Republican-inspired "Dream Act" that would grant citizenship to illegal immigrants who were under age 16 when brought to the United States. They must hold a high school diploma and have done two years of college or service in the military. A broader Dream Act backed by Democrats has stalled in the U.S. Congress.
"I'm taking a look at his proposal. It has many features to commend it, but it's something that we're studying," said Romney.
Rubio was the latest potential vice presidential pick to team up with Romney on the campaign trail.
Others who have been on what could be seen as a running-mate test drive include Wisconsin Congressman Paul Ryan, Virginia Governor Bob McDonnell, Ohio Senator Rob Portman, New Jersey Governor Chris Christie, South Carolina Governor Nikki Haley and New Hampshire Senator Kelly Ayotte.
The body language between Romney and Rubio was warm and Romney repeatedly handed off the microphone to Rubio to respond to questions.
The joint visit was planned when Pennsylvania, which votes on Tuesday, was expected to be close between Romney and his last conservative challenger Rick Santorum, who has since pulled out of the campaign.
At his news conference, Romney opted not to get into his service as a Mormon missionary in France in the 1960s when a French television crew asked him to describe his favorite memory of France.
"I think the best memories were with my wife on vacations, from time to time in France. The last vacation we had there, walking around the city of Paris, not just in the Champs-Elysees, but also over to the Jardin of Luxembourg and around the city," he said.
(Editing by Mohammad Zargham)