Mitt Romney’s biggest donors and fundraisers are descending on Utah’s exclusive Deer Valley resort this weekend for what invitees are calling Republicanpalooza: a two-day retreat featuring Karl Rove, Condoleezza Rice, Jeb Bush and John McCain.

But the highlight for the 700 guests, who either contributed $50,000 or raised $250,000 for the campaign, will be unfettered access to Romney himself, who will deliver a speech and mingle at a cookout beside the ski jumps at Olympic Park.

Romney, who survived a prolonged and cash-draining Republican primary process, has accomplished what many once thought impossible: He is keeping pace with President Barack Obama’s vaunted fundraising operation, which demolished records four years ago.

To a remarkable degree, interviews with donors, fundraisers and staff show, that financial haul has hinged on Romney’s clout in the business world and his relentless personal cultivation of contributors, a political ritual for which Obama has shown little enthusiasm and McCain, the last Republican presidential nominee, displayed outright disdain.

Romney has repeatedly invited top-flight donors to his home on Lake Winnipesaukee in New Hampshire for intimate gatherings where he serves cookies baked by his wife, Ann. He has spent hours meeting with wealthy would-be backers from Cincinnati to Los Angeles who remain on the fence. And he has held seminars on issues that animate supporters, like Israel, education and energy.

The result: an infusion of high-dollar donations, which account for the vast majority of Romney’s campaign contributions and helped him out-raise Obama last month, a symbolic and psychological milestone that set off alarms within the Democratic political world.

Romney, it turns out, is a thoroughbred fundraiser. After spending years as a private equity executive talking the wealthy into parting with their money, he has had little trouble persuading contributors, especially entrepreneurs, to invest in his vision of a Romney White House that is pro-business and anti-tax.

“He has a tremendous aptitude for this,” said Woody Johnson, owner of the New York Jets and one of Romney’s earliest financial bakers.

The campaign’s reliance, however, on wealthy donors and its refusal to disclose the identity of his bundlers, as the Obama campaign has done, has drawn criticism from advocates of campaign finance reform, and reinforced Romney’s image as a candidate whose greatest appeal is with the country’s elite.

Not long ago, Romney visited the Park Avenue office of Kenneth G. Langone, a co-founder of the Home Depot who had called for Gov. Chris Christie of New Jersey to run for president this year. After an hour, Romney had won over his fellow businessman.

“I didn’t look or talk to him any differently than a guy coming in here pitching me on a start-up company,” Langone said. “They are exactly the same. I am investing in a person.”

Obama, of course, is an adroit fundraiser whose team pioneered — and still dominates — Web-based outreach to small donors. He has used the mechanisms of incumbency to his advantage, inviting donors to state dinners and appointing them to his Jobs Council. But the president’s discomfort with stroking donors is well known, prompting some to complain that he can be chilly and inattentive.

Democrats express grudging admiration for Romney’s fundraising prowess.

“He has shown a great ability to listen to his donors and show he is engaged with them,” said Robert Zimmerman, a Democratic National Committee member and an Obama fundraiser. “The fundraising strategy is about building relationships, not just about raising money.”

Now, as top-tier donors and bundlers like Langone reach their legal limits, Romney is pursuing a new breed of donors — midlevel millionaires far from the corners of finance, who run dry cleaning chains and small industrial companies and share the candidate’s small-government ideology.

The campaign recently held a conference call for 30 car dealership owners in which Romney’s fundraising chief emphasized the importance of family-owned businesses. The dealers have since become a reliable source of donations.

Sprawling campaigns have long struggled to keep up with the demands of their donors, many of whom feel entitled to instant responses to questions and requests for access.

The Romney campaign, by contrast, has flooded them with communications. There are daily and weekly conference calls, many featuring senior campaign members who offer updates on strategy and policy, and a software system that encourages friendly competition by allowing donors to monitor giving from friends whom they recruited. Several supporters recalled receiving all-hours phone calls and emails from Spencer Zwick, Romney’s fundraising chief, who has a 24-hour rule: All messages are returned within a day.

“I keep hearing from people who are shocked at the follow up and follow through,” said Jack Oliver, who oversaw fundraising for George W. Bush’s presidential campaigns and is close to the Romney campaign.

It is the attention from Romney, however, that has left the deepest impression on donors, who said they felt like extended members of the family, much in the way Bush embraced contributors. Bush became famed for immersing donors in his Texas life during retreats in Austin and following up with handwritten thank yous.

“This is the Bush operation on steroids,” said Anthony Scaramucci, a New York financier who has raised more than $1 million for Romney.

Scaramucci said he relished his time at Romney’s house in New Hampshire, where the candidate gave a slide show about campaign strategy and spoke with guests on a deck overlooking the lake.

“People love being able to say they went to Romney’s house,” Scaramucci said. “It’s an attractive magnetron for the campaign.”

The campaign has organized much of its outreach around issues that energize contributors, like Israel. In May, it held a daylong series of policy discussions with donors at Romney’s headquarters in Boston, ending with an appearance by the candidate himself.

Philip Rosen, a Romney donor active in Jewish causes, said the presence of the candidate “shows he cares personally, which is something we know, but it’s important to see. For those who did not have a personal relationship with him, it’s essential.”

There is a harder edge to the operation, whose corporate-style punctiliousness and accountability is an extension of the candidate himself. Fundraisers who repeatedly miss goals are quietly but firmly eased out of state chairmanships, according to a person familiar with the matter.

The campaign has been criticized for tying donations of $50,000 or more to guest packages for the Republican National Convention.

Johnson, the Jets owner, played down the issue.

“I don’t have the feeling at all that any of this gets you any special access to anything untoward,” he said.

Romney has ramped up outreach to smaller donors, online and through lotteries to have lunch with him and his wife. But such donors will not be invited to Utah this weekend, where Rove and Fred Barnes, executive editor of The Weekly Standard, will host a panel on the media’s role in presidential politics, and Rep. Paul Ryan of Wisconsin and Meg Whitman, the chief executive of Hewlett-Packard, will discuss the government’s impact on the economy.

Ray Washburne, a Romney fundraiser attending the retreat, said the campaign had proven deft at “making donors feel like they are inside players.”

“We feel very appreciated,” he said.