CHICAGO - As the 2012 Olympic flame was extinguished in London tonight, President Obama exhorted a group of loyal supporters huddled in the front yard of his Hyde Park home to adopt the Olympic spirit and sprint to the finish in this highly competitive presidential race.

"I just want to remind you this is not going to be a race like Usain Bolt where we're like 40 yards ahead and we can just start jogging 10 feet before the finish line," Obama said of the Jamaican gold medalist known as the fastest man in the world. "We're going to have to run through the tape."

The president was playing host to 100 donors to his re-election campaign who paid $40,000 apiece to attend. The event, his third of five fundraisers scheduled today, was expected to raise more than $4 million for the campaign, according to Democratic officials.

Obama exuded confidence in his chance of winning in November, but seemed eager to encourage his fans not to become complacent.

"Every election, presidents or candidates will say, 'this is the most important election of my lifetime,'" he said. "This is the most important election of my lifetime," he deadpanned to applause from the crowd.

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It is "more important than 2008 in a lot of ways" because back then "there was a sense that although we were entering into" an economic crisis and "there did still seem to be some overlap between the parties in terms of the things we needed to get done to ensure opportunity for the next generation."

Obama said that with the entry of Rep. Paul Ryan into the race the contrast between visions for the future - and what's at stake - has become even clearer.

"We can only win it because of you, because of the enormous support and effort and sacrifice that all of you have been willing to make," Obama said.

Shortly after wrapping up his remarks, the president walked down the the block from his private residence to a fourth fundraiser of the day at a neighboring home.