The USA TODAY/Gallup poll, taken Friday through Sunday, found that Clinton has widened her lead over Obama. Her support was at 48 percent, up 8 percentage points from three weeks ago, while Obama's support was down two percentage points at 26 percent.

The 22-point gap between the two is nearly double the margin found in the July 12-15 poll.

Among Democrats and independents who "lean" Democratic, former North Carolina senator John Edwards is at 12 percent.

Among Republicans, the race is stable: former New York mayor Rudy Giuliani at 33 percent, former Tennessee senator Fred Thompson at 21 percent, Arizona Sen. John McCain at 16 percent and former Massachusetts governor Mitt Romney at 8 percent.

The Democratic race is much closer in the states where opening contests will be held and campaigning is already fierce, the USA Today newspaper reported.

In the survey, Democrats and Democratic-leaning independents by overwhelming margins say Clinton would do a better job as president than Obama in handling terrorism, the Iraq war and relations with unfriendly nations.

If the nomination narrows down to two, Clinton was preferred over Obama by 59 percent to 36 percent.

Also in the poll, President George W. Bush's approval rating ticked up to 34 percent, better than his low of 29 percent in July. The approval rating for congressional Republicans was 29 percent and 37 percent for congressional Democrats -- both new lows in the eight years since the question was first asked.

The survey of 1,012 adults has an error margin of +/- 3 points for the full sample, and 5 points for the Republican and Democratic subsamples.