The Associated Press

NORFOLK, Va. — Republican presidential candidate Mitt Romney has decided on a running mate and will announce his decision Saturday morning in Norfolk, Va., his campaign said tonight.

Romney advisers wouldn’t disclose the name.

In a statement issued tonight, the campaign would only go so far as to say that the running mate would be revealed at 9 a.m. EDT [6 a.m. PDT] at the start of a four-state bus tour at the Nauticus Museum. Berthed at the museum is the USS Wisconsin — possibly a hint about Romney’s choice.

Wisconsin Rep. Paul Ryan, the seven-term Wisconsin congressman, has been the focus of speculation in recent days. Conservative pundits have been urging Romney to choose Ryan in large part because of his authorship of a House-backed budget plan that seeks to curb overall entitlement spending and changes Medicaid into a voucher-like system to save costs.

On Thursday, Romney told NBC that he wants a vice president with “a vision for the country, that adds something to the political discourse about the direction of the country.”

The Wall Street Journal, in an editorial on Thursday, praised Ryan as a strong choice for Romney: “The case for Mr. Ryan is that he best exemplifies the nature and stakes of this election. More than any other politician, the House budget chairman has defined those stakes well as a generational choice about the role of government and whether America will once again become a growth economy or sink into interest-group dominated decline.”

Party officials say Republican National Committee Chairman Reince Priebus has been convinced for days that Romney had settled on Ryan, according to multiple people who spoke with the chairman. Priebus, who, like Ryan, is from Wisconsin, is expected to attend Saturday morning’s announcement.

Others said to be in contention were Ohio Sen. Rob Portman and former Minnesota Gov. Tim Pawlenty.

Pawlenty was maintaining his Saturday schedule campaigning for Romney in New Hampshire, an official close to Pawlenty’s political team said. The person spoke on the condition of anonymity because the person was not authorized to speak ahead of the formal announcement.

Most of Romney’s staff learned of the looming announcement during a 10 p.m. EDT conference call today about an hour before the campaign issued a statement. The identity of Romney’s pick was not disclosed during the call.

Earlier in the day, Romney’s campaign briefed reporters on the bus tour, making no mention of the impending vice presidential announcement.

“The governor keeps very close counsel on that, and I have no guidance,” adviser Eric Fehrnstrom said of any potential event.

Romney’s son Tagg joined Ryan at a funeral for victims of the Wisconsin Sikh temple shooting with Ryan on Friday. The younger Romney said he is planning to campaign in New Hampshire over the weekend and is not attending the bus tour.

Romney’s choice comes as he tries to repair an image damaged by negative Democratic advertising and shift the trajectory of a campaign that’s seen him lose ground to President Barack Obama.

The vice-presidential selection will dominate headlines, and Romney’s team has been relentlessly teasing the announcement for weeks.

Romney’s bus tour was expected to include appearances with Portman, as well as two others talked about as possible contenders for running mate: Virginia Gov. Bob McDonnell and Florida Sen. Marco Rubio.

The tour starts Saturday and will take Romney through four must-win states in as many days: North Carolina, Virginia, Florida and Ohio. All are battlegrounds where Obama won in 2008. While Obama could afford to lose in one or more of them and still reach the 270 electoral votes needed for another term, Romney almost certainly needs all four to beat him.