Mitt Romney has a problem. He hasn't even secured the Republican nomination yet, and the chattering classes are already going on about how his pick for running mate might make or break his campaign.

With months to go before August's Republican National Convention, that's all it is at this point — chatter. Fun, pointless chatter that keeps us politics nerds reading, retweeting and speculating for months.

And what's the harm in that? No one picked Sarah Palin four years ago, so the speculation net's being casted pretty wide this time around.

But after the fascinating, polarizing whirlwind that was Palin's selection in John McCain's ultimately doomed presidential bid, the overwhelming message to Romney's camp from this chatter is clear: No pressure, dude.

The speculation over the vice-presidential pick usually centres on what the media perceives as a candidate's weakness in the eyes of voters, either on issues (like changing your views on abortion, downplaying your own health-care reform record), biography (saying your wife drives "a couple of Cadillacs" and some of your friends are "NASCAR team owners") or even filling a geographic/electoral math hole (Ohio, Florida, step right up).

The VP pick is "all about either shoring up a weakness of yours to keep people from talking about it or emphasizing, 'Here’s what this election's about,' " said John Barry Ryan, a political science professor at Florida State University who conducts research on campaigns and media coverage of elections.

Whoever it is, the pick shouldn't be a drag on the ticket "because it will never be that much of a boost," he added.

The contenders

Marco Rubio: The Republican version of a rock star, Rubio has recently tried to downplay talk of him being the Republican VP nominee. Last week, he praised Jeb Bush as a "fantastic choice" for the job, in what could be an attempt to show he's not trying to steal the spotlight from Romney.

"It’s like any relationship, in that you don’t want to look better than your partner," Ryan said.

Rubio, a rookie senator from the battleground state of Florida, could light a spark among the party's right-wing members who are less than thrilled with Romney's conservative credentials. Rubio, Ryan said, "has the ability to speak in a way that the further-right tea party parts of the Republican party like, but without doing it in such a way that alienates more moderate voters."

At the same time, Rubio could improve Republican attempts to build bridges with America's growing Hispanic community, whose members have traditionally favoured Democrats and likely still have fresh memories of Romney's tough stance on illegal immigration during the primaries.

The charismatic son of Cuban immigants who fled Fidel Castro's regime also brings a certain X-factor to the Republican ticket, in that he's "young, tells a good story and looks good," Ryan said. While selecting a Cuban-American from a state where the community has long held a position of influence will likely bolster Romney's chances in Florida, the move won't automatically deliver the Sunshine State's electoral college votes to the Republican ticket in November.

Rob Portman: Heralded as this week's safe pick, the Ohio senator has a legislative and budget background that could be used to emphasize the Romney campaign's message of being more qualified economic stewards than Barack Obama. Portman also represents a swing state the Republicans need to win to get back the White House.

Online news site Buzzfeed recently conducted an informal survey of Republican insiders and found Portman was their top choice for the vice-presidential slot.

But Portman was also head of the Office of Budget Management during the George W. Bush administration, and fiscal critics — especially conservatives — have long pointed to Washington's repeated failure to manage the behemoth federal budget at all.

Jeb Bush: Bush, a popular former Florida governor, brings his family's presidential pedigree and was rumoured to be a potential convention saviour for Republicans if Romney failed to secure the delegates needed to become the party's nominee. Bush effectively ended that dream last month by endorsing Romney after his win in the Illinois primary.

Bush could sit 2012 out for the sake of his own ambitions, Ryan said, citing whispers in Florida circles that Bush might want to run in four years. If he does, he wouldn't mind too much if Romney lost now.

“I see no advantage to him being the vice-presidential nomination because if they win, eight years from now, time may have passed him by, and if they lose, he's now known as the guy who lost with Mitt Romney,” Ryan said.

But Bush could still say yes to secure a legacy beyond his state without all the pressures and scrutiny of being commander in chief. "Maybe he doesn’t want to be president, but wants that spot in history," Ryan added.

Tim Pawlenty: The former Minnesota governor, who was on the vice-presidential short list for McCain's 2008 campaign, ended his own presidential campaign last August after failing to generate any enthusiasm for his bid.

Popular among tea party conservatives and Romney's campaign, Pawlenty won't overshadow the presidential candidate in a way similar to Palin's presence over McCain in 2008.

Paul Ryan: A fiscal hawk, and vocal critic of Obama's health-care legislation, the Wisconsin congressman's stature has continued to grow in the party and had sparked talk about a 2012 presidential bid. As chair of the House of Representatives budget committee, Ryan is the public face and private crafter of the Republicans' most recent budget proposal, which was immediately blasted by Democrats.

For all his profile, many within the Republican establishment view Ryan's latest budget draft as a "political disaster," Ryan said.

Nikki Haley: The youngest governor in the nation is viewed as a rising star in the Republican party. Haley, the governor of South Carolina, has been a vocal supporter for Romney in her home state. Nevermind that he lost South Carolina's primary to Newt Gingrich.

For her part, Haley, a South Carolina-born Indian-American, recently said in a lengthy profile in Vogue magazine that she would decline the VP nomination if offered.

Chris Christie: The firebrand New Jersey governor and former prosecutor is highly popular in Republican circles for slashing government spending and taking on unions since being elected in 2009, so much so that many in the party wished Christie had run for the top of the ticket. Instead, he's stumped for Romney during the primaries, often as the candidate's warm-up intro act.

And the big guy sure can warm up a crowd. At a New Hampshire Romney event in January, Christie shot down female Occupy hecklers with a Jersey comeback that was perhaps too PG-13 rated for presidential campaigns and showed Christie might burn a little too brightly standing next to Romney.

Kelly Ayotte: Elected to the Senate in 2010, Ayotte, a former New Hampshire attorney general, has been an early Romney backer and represents another crucial state for Republicans in November's presidential election.

"Romney's probably got to win New Hampshire" to win the presidency, according to FSU's Ryan, who cited the state's electoral votes as key for George W. Bush in the hotly contested and still controversial 2000 presidential election.

“You get a woman from New Hampshire, a pick that the news will spin as smart. It will give him a good couple of weeks, and she won’t embarrass him on the campaign trial and won't look more interesting than him."