WOLFEBORO, N.H. (AP) — Even Mitt Romney's shopping cart becomes a clue when trying to solve the political world's biggest mystery.
The Republican presidential candidate stopped by a supermarket near his New Hampshire vacation home to buy cases of water, Wild Cherry Pepsi and Greek yogurt.
"I got some folks coming over today," Romney told reporters Monday as he loaded groceries into a black Chevy Suburban.
Would those guests include potential running mates? Romney's only response was laughter.
He has repeatedly shrugged off questions about his vice presidential selection. But as the clock winds down before this month's Republican National Convention, political observers are grasping at the slightest hint.
[Related: Romney campaign preps VP app]
Once his shopping list became public, people instantly began speculating on Twitter — half-jokingly — about the yogurt and soda preferences of those on the vice presidential short list. Some reporters scrambled to study the travel schedules of potential contenders while others checked on how much longer Romney's wife, Ann, would spend with the family horse at the London Olympics. Romney isn't likely to make his decision public without her at his side.
There are no clear answers. The Republican presidential candidate's senior aides have teased for weeks that his selection of a vice presidential contender could come any day. But that's all they're saying. And in a tight-knit campaign known for discipline, the handful of people involved in the selection process have refused to share whether Romney has reached a decision or reveal who's being vetted.
[Related: Gen. Petraeus in the running?]
The level of secrecy is so great that some of Romney's own staffers aren't sure whether schedules, Twitter messages and public statements are being manipulated to throw people off track. Misinformation, after all, is an undeniable reality in modern presidential politics.
"The big VP announcement is coming soon and the buzz here at campaign headquarters is exciting," campaign manager Matt Rhoades wrote in a fundraising message late last week that offered donors a chance to meet Romney's running mate in person.
Romney did not meet with prospective candidates Monday. Instead, he shared his groceries with a few senior advisers, including the head of his vice presidential search, Beth Myers. Last week, Myers told supporters they could "be the first to get the VP scoop" by downloading a new mobile phone app.
The pieces are in place. The campaign has hired a staff for the running mate and set detailed fundraising expectations. Romney has studied candidates in YouTube videos and watched others in person. Aides have pored through tax filings and personal histories to prevent any surprises.
Above all, Romney is expected to select someone ready to assume the presidency on Day One. The standard has been applied — at least in part — because of problems surrounding the GOP's last vice presidential nominee, former Alaska Gov. Sarah Palin, who struggled to inspire confidence among the broader electorate.
The Romney campaign also wants a team player. Possible running mates such as former Minnesota Gov. Tim Pawlenty, Ohio Sen. Rob Portman, Louisiana Gov. Bobby Jindal and Wisconsin Rep. Paul Ryan have been aggressively campaigning on Romney's behalf across the country in recent months.
Portman, Florida Sen. Marco Rubio and Virginia Gov. Bob McDonnell are expected to join Romney on segments of a bus tour that begins Saturday in Virginia and moves to North Carolina, Florida and Ohio. Pawlenty has campaign events scheduled for New Hampshire next weekend. And each of the men has scheduling holes in the coming days that could allow him to slip away quietly for a big announcement.
More clues lie among the speaker's list for the upcoming Republican National Convention. Romney's pick probably wouldn't have scored one of the spots; the convention speakers now include South Carolina Gov. Nikki Haley, former Arkansas Gov. Mike Huckabee, New Mexico Gov. Susana Martinez , former Secretary of State Condoleezza Rice, former Pennsylvania Sen. Rick Santorum and former Florida Gov. Jeb Bush.
Will Romney go boring or bold?
But nothing is for certain in this game. Presidential candidates historically have gone to great lengths to keep their deliberations secret until they're ready to announce a choice.
When George W. Bush settled on Dick Cheney in 2000 more than a week before his running mate was to be announced, aides worried that the secret might not hold. To throw off reporters, campaign architect Karl Rove told a campaign aide known to leak information to reporters that former Sen. John Danforth of Missouri had emerged as a top candidate. Three television networks reported the news, giving the campaign some breathing room for Cheney's announcement, Rove wrote in a memoir.
Romney may be doing some head faking as well. The Drudge Report, a conservative website with ties to the Romney campaign, posted a story last month suggesting that Rice had emerged as Romney's top choice. Rice previously had said "there is no way" she would serve as vice president. She also described herself as "mildly pro-choice," which would violate Romney's promise to select a candidate who opposes abortion rights.
Just don't ask Romney to comment on the mystery directly. Campaigning in the Las Vegas area over the weekend, he told reporters he would absolutely "decide and announce my running mate before the third day of the Republican convention."
That's not much help. The third day of the four-day convention is usually when the running mate addresses the delegates.
"Other than that," Romney said, "I've got nothing for you."
___
Associated Press writer Brian Bakst in Minnesota contributed to this report.