Image credit: David Goldman/AP Photo

It will be days before public opinion polls will have tallied how President Obama and Mitt Romney performed at the first presidential debate. But, while the odds are still with the president, betting men have been casting their lots for Romney.

On both Intrade, an Ireland-based online betting market, and BetFair, its English counterpart, the odds that Romney will win the election spiked in the aftermath of his strong debate performance as bettors poured thousands of pounds and dollars into predicting who will win the White House in November.

Bettors on Intrade, primarily Americans wagering millions, boost Romney's chances 7 percentage points from his closing value on Tuesday to his closing value Thursday, the largest spike Romney has seen on the 2012 market.

Obama's odds, on the other, dropped 14 points from a 79-percent high the day before the debate to a 65-percent low the day after.

On Betfair, which caters to bettors outside the U.S. and deals in British pounds, Romney's odds didn't rise quite as much: 6 percentage points from a 19 percent chance of winning last week to a 25 percent chance following the debate.

The GOP nominee's confident debate showing inspired bettors to place more than 20,000 pounds in wagers that he will beat Obama. By the time the candidates left the stage Wednesday night, 5.5 million pounds had been wagered between Betfair customers on who would win in November.

But the Betfair odds are still largely in the president's favor.

"Having been solid Obama territory for the last two months, last night was the first time Betfair's market reacted positively to Romney," Betfair spokesperson James Midmer said. "However, despite some of the hype surrounding his debate performance, the market reflects that there is still a sizable gap to close among America's key demographics, which will take more than a decent 90 minutes in front of the cameras."

As of Thursday morning, Betfair customers gave Obama a 75 percent chance of winning the election. That's down 6 percentage points from last week, but still more than double Romney's odds. During the debate alone, betters waged 71,000 pounds on the president's winning in November.

Betfair accurately predicted who would win the White House in 2004 and 2008, the only years it has collected bets on the race. This is only the second U.S. presidential election Intrade has taken wagers on. The market correctly predicted the last presidential election, when Obama beat Arizona senator John McCain.