Fresh off the best fundraising stretch of his presidential campaign, Mitt Romney plans to spend this weekend strategizing and fraternizing with his biggest bundlers at a posh resort in Park City, Utah.

The presumptive Republican nominee and his senior advisers and aides are hosting two days of policy sessions and campaign strategy discussions at the Deer Valley resort for more than 100 top fundraisers and their spouses. Those who raised more than $100,000 are expected to attend.

More than a dozen Republican heavy-hitters are scheduled to join the private retreat as special guests. According to a fundraiser who is attending, they include some GOP stars thought to be in contention to be Romney’s vice presidential running mate: Rep. Paul Ryan (Wis.), Louisiana Gov. Bobby Jindal and Sen. John Thune (S.D.).

George W. Bush strategist Karl Rove, who helps run American Crossroads, the well-funded GOP super PAC, is planning to speak at the retreat, said the fundraiser, who was not authorized to publicly discuss the event and spoke on the condition of anonymity. Rove’s appearance could raise questions because of laws barring any coordination between super PACs and campaigns.

Sen. John McCain (Ariz.), the party’s 2008 presidential nominee, also is scheduled to attend, according to the fundraiser.

Other expected guests include former secretaries of state Condoleezza Rice and James A. Baker III, former Florida governor Jeb Bush, strategist Mary Matalin, and commentators Bill Kristol and Fred Barnes.

The meeting coincides with good news for Romney’s campaign, which for the first time last month raised more money than President Obama. The campaign and the Republican National Committee jointly raised $77 million in May, outpacing the $61 million that Obama and the Democratic National Committee reported collecting.

In a report to the Federal Election Commission on Wednesday, the Romney campaign said it spent $15.6 million in May. Obama campaign officials reported spending nearly three times that, $44 million, shelling out cash faster than they could raise it. That allowed Romney to begin catching up in the cash he has on hand — $107 million for his campaign and the RNC, compared with $147 million for Obama and the DNC.

Obama officials predicted Wednesday that they will be badly outspent on television ads, suggesting that Republicans and allied groups would invest $1.2 billion in airtime.

Restore Our Future, a super PAC founded by former Romney aides to boost his candidacy, told the FEC that it raised nearly $5 million in May and spent nearly all of it, mostly on ads. That report did not include $10 million donated by casino magnate Sheldon Adelson this month. The PAC launched a $7 million ad buy in eight battleground states this week.

Also planning to attend the Park City gathering are many of Romney’s top aides and advisers, including former Utah governor Mike Leavitt, whom the candidate has tapped to begin planning his transition to the White House should he win in November.

Romney’s finance officials have touted the retreat as a way to reward top-performing bundlers, who make their own donations and then raise many times that from their networks of friends and associates.

The retreat, which will be closed to the news media, is set to begin Friday with policy question-and-answer sessions with Romney. The donors will be briefed on campaign strategy and will spend considerable time planning ways to build on the initial general-election fundraising success.

At a May fundraiser, New York Jets owner Woody Johnson, chairman of Romney’s New York finance operation, called the retreat “very, very important” for the campaign.

The event is to be a sort of homecoming for Romney, who lived in Park City for three years when he helmed the 2002 Winter Olympics. Two of his sons, Josh and Ben, live in the area.

Receptions and dinners with Romney and his guests are planned for Friday and Saturday night, with dessert and dancing on the agenda for Saturday evening. The festivities continue Sunday with golf.

“You get to go home and tell your friends and family and colleagues, ‘I just spent the weekend with Mitt Romney,’ and all of that is really good for morale,” said a second fundraiser who will be there and who also was not authorized to speak publicly.

Staff writers T.W. Farnam and Dan Eggen contributed to this report.