Senator John McCain faced alienating the influential Christian wing of the Republican Party after it was disclosed that he is a keen gambler with extensive ties to the gaming industry.

The 72-year-old is a lifelong gambler who favours the craps tables and continues to play today, 'The New York Times' reported at the weekend.

Mr McCain's habit, which appears to take the form of a monthly binge rather than a daily addiction, could prove damaging in a very close contest with Senator Barack Obama, his Democratic rival for the US presidency.

Evangelical Christian Republicans have never been comfortable with Mr McCain, seeing him as too secular and too moderate.

In addition, his claims to be a Washington outsider have also been thrown into doubt after his extensive ties to the gambling industry and its lobbyists were disclosed by the newspaper.

The Obama campaign seized on this to call into question his claims to be a "maverick", intent on changing the system.

"Gambling in casinos that you regulate with the lobbyists that represent those casinos is more of the same broken, special interest-driven politics that has dominated Washington," said Dan Pfeiffer, Mr Obama's spokesman.

Former members of Mr McCain's staff said he indulged in a marathon session at the Foxwoods Resort Casino in Connecticut in 2000 after he had lost out in the Republican presidential primary to George W Bush.

The casino is run by the Pequot tribe, which has contributed heavily to Mr McCain's campaigns and has transformed Foxwood into one of the world's largest casinos.

Statistics from the non-aligned Centre for Responsive Politics show that Mr McCain is the largest recipient of money from the casino industry in Congress, outside the gambling meccas of Nevada and New Jersey, and that 40 of his top fundraisers and advisers have ties to the gambling industry.

In this presidential race he has received twice as much from the industry as Mr Obama.

As senator of Arizona, the state with the third-highest native American population, Mr McCain was an early champion of legislation that allowed tribes to set up casinos on their reservations.

The industry exceeded all expectations, booming to reach an annual turnover of stg£10bn (€12.6bn) with more than 400 casinos spread across the country.

The two presidential candidates were, meanwhile, awaiting the findings of the first full opinion polls conducted since their presidential debate last Friday night.

The two men debate again on October 7, while Sarah Palin and Joe Biden, their running mates, will meet on Thursday in a clash expected to draw a large television audience.