Kirk Wagar, a Florida lawyer who has raised more than $1 million for President Obama’s re-election bid, had his choice of rooms for the Democratic convention at Charlotte’s Ritz-Carlton or Westin hotels and nightly access to hospitality suites off the convention floor.

Jay Snyder, a New York financier who has raised at least $560,000 for Mr. Obama, was entitled to get his picture taken on the podium at the Time Warner Cable Arena.

And Azita Raji, a retired investment banker who has raised over $3 million for Mr. Obama — more than almost anyone else during the last two years — could get pretty much anything that she wanted last week in Charlotte: briefings with senior Obama officials, invitations to post-speech parties, along with “priority booking” at the city’s finest hotels.

In the race for cash, Mr. Obama often praises his millions of grass-roots donors, those die-hards whose $3 or $10 or $75 contributions are as much a symbol of the president’s political identity as they are a source of ready cash. But his campaign’s big-dollar fund-raising has become more dependent than it was four years ago on a smaller number of large-dollar donors and fund-raisers.