DENVER  The sun dipped behind the towering sandstone monoliths of the Red Rocks Amphitheatre on a recent evening as donors to the Democrats' national convention sipped mojitos and snacked on bison burgers at a private reception. They later took in an invitation-only concert featuring Sheryl Crow and the Dave Matthews Band.

A day later, big givers to the committee raising money for Democratic senators gathered in a plush hotel ballroom for a private breakfast meeting with the candidates. When Barack Obama accepts his party's nomination at the Invesco football stadium here Thursday, major contributors will watch from luxury skyboxes high above the field.

The courting of donors and fundraisers is in high gear at the Democratic National Convention. Those who helped underwrite the four-day event, raised money for congressional candidates or worked to bring in hundreds of thousands of dollars for the national party to aid Obama's presidential campaign mingle with celebrities and politicians at dozens of parties, receptions and luncheons.

"It is non-stop," Ben Barnes, a former Texas lieutenant governor, said of the whirlwind of activities. Barnes has contributed more than $100,000 to federal candidates, parties and congressional fundraising committees in the past two years, campaign records show. "After four or five days, it becomes a physical endurance test," he said. "Can you stay up past 1 o'clock in the morning? Can you go to one more party?"

Craig Holman of Public Citizen, a liberal-leaning watchdog group, said these activities are inappropriate. "The more donors chip in, the more access they buy," he said. "And these are some of the biggest lobbying corporations on Capitol Hill."

Stacie Paxton, a spokeswoman for the Democratic National Committee, and Nick Shapiro of the Obama campaign said the events are a way to thank donors.

"Many of our top fundraisers in attendance can attend a range of different events thanking them for the work they have been and are doing to help change Washington," Shapiro said in an e-mail.

Some of the biggest rewards go to companies that have helped pay for the convention.

Offerings include "exclusive events" with national Democratic leadership, according to the sponsorship guide. "Silver" sponsors who gave at least $100,000 receive convention credentials. Xcel Energy spokesman Joe Fuentes said his company received an Invesco skybox because it contributed $1 million.

"This is a way for us to show our appreciation," said Chris Lopez, spokesman for the Denver Host Committee, which raised more than $40 million in private convention funds. "I don't think there is any undue influence" on politicians as a result, he said.

Donors to next week's Republican National Convention in St. Paul will enjoy similar benefits, including luxury-level seats in the convention hall and preferred bookings at downtown hotels.

Other offerings for donors at the Democratic confab include an invitation-only briefing today with top Obama aides, said Mark Aronchick, a Democratic National Committee fundraiser from Philadelphia. A schedule for the Senate Democrats' fundraising arm shows receptions at downtown restaurants for its big givers.

Don Fowler, a former Democratic National Committee chairman, said the care and feeding of top donors at a convention gives party leaders the chance to reward contributors and motivate them to continue raising cash for the sprint to Election Day.

"You want to be nice to them, make sure they have nice hotels and good transportation and good seats," he said. "The party also can provide access to important decision makers. … That's what pleases contributors."

The Price of Power is an ongoing series tracking the role of money in politics.