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

“Mr. 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 one-on-one 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.”