More than 350 generous campaign contributors -- some of them donating $28,500 to dine with a presidential candidate -- cheered Democrat Barack Obama on Wednesday at an exclusive fundraiser for him at the Hilton Minneapolis Hotel.

"I am absolutely convinced we will win Minnesota," the Illinois senator said to roaring applause.

Among those standing for his speech in a ballroom were Karl Schmidt and his wife, Ellen, of Minneapolis, who an hour earlier had a private picture taken with Obama. The campaign charged $5,000 for such photos.

"He seems to connect well with people," Karl Schmidt said. "He's very charming."

Schmidt is the chief operating officer for an auto dealership and said that "most of my peers are Republicans," some of whom contributed to Arizona Sen. John McCain, the presumptive GOP presidential nominee. "So it's a little odd."

It cost $1,000 to attend the general reception at which Obama spoke. His campaign didn't disclose how many people donated $5,000 to have their picture taken with him.

But 50 people paid $28,500 each to dine privately with him. The menu: lettuce cup salad, beef medallions, followed by birthday cake from Sen. Amy Klobuchar, D-Minn., and other Minnesota supporters. Obama turned 47 on Tuesday.

Contributions were to be split between Obama and the Democratic National Committee.

Among those at the general reception were Minneapolis Mayor R.T. Rybak, St. Paul Mayor Chris Coleman and U.S. Senate candidate Al Franken.

Obama played to the hometown crowd, calling Rybak "somebody who supported me before I started to run for president."

The presumptive Democratic nominee for president customized his standard stump speech in recognition of the importance of the ethanol industry, but suggested possible changes in calling for "a new set of biofuels that will work for Minnesota and Middle America."

Obama made a mark early in the primary season by relying heavily on small donations -- less than $100 -- raised over the Internet to take a fundraising lead over McCain and Democratic rival Sen. Hillary Clinton. But Wednesday's event illustrates again the power of big donors.

Schmidt said he and his wife decided to attend the fundraiser because "our economy is a mess, we're at a point where we have an opportunity for some change. That's why we came."

Still, he said Obama's address seemed similar to other speeches he's heard and that the senator said "nothing really concrete."

Earlier in the afternoon, state Republican Party chairman Ron Carey held a news conference outside the Hilton to mock Obama's recent energy statements. Last week, Obama said that as much oil could be saved by keeping cars tuned up and tires properly inflated as could be obtained through increased drilling.

Carey said that instead of real answers for the country's energy woes, Obama was offering "a tire pressure gauge [as] a better energy solution than drilling for more oil in America."

To underscore the point, GOP staffers handed out tire gauges labeled "Obama's energy plan." About a half-dozen young Republicans held large tire gauge props and fake tires.

On Tuesday, at a campaign stop in Ohio, Obama had defended his suggestion that properly inflating tires would improve gas mileage and also accused Republicans of "lying" about the scope of his energy plan., a feature of the St. Petersburg Times, said Obama's tire inflation idea is plausible.

Staff Writer Kevin Duchschere and the Los Angeles Times contributed to this report. Pat Doyle • 651-222-1210