Many supporters of Hillary Clinton and Barack Obama are ready to switch sides and vote for Republican John McCain in November if their candidate doesn't win the Democratic nomination, according to a new poll.

A second poll out Wednesday shows most voters - including 85 percent of Democrats - believe there's a chance that the battle between rival party presidential hopefuls, Clinton and Obama, will not be resolved before the party convention in August.

Among people who identified themselves as Hillary Clinton supporters, 28 percent said they would vote for presumptive Republican nominee McCain if Obama is his opponent, the March 7-22 Gallup Poll daily election tracking survey found.

The same poll found that 19 percent supporters of Obama, bidding to be America's first black president, would switch sides and vote for McCain if Clinton, hoping to be the first woman US chief executive, is the Democratic candidate.

The survey interviewed 6,657 Democratic voters nationwide and had a margin of error of two percent. Gallup analysts note that the results could change by November, by which time Democrats will have made great efforts to unify the party.

'(The results) suggest that some Clinton supporters are so strongly opposed to Obama (or so loyal to Clinton) that they would go so far as to vote the 'other' party's candidate next November if Obama is the Democratic nominee,' Frank Newport of Gallup said of the survey's findings.

Newport noted that the poll's results are likely the result of the heated battle for the nomination, and the number of the party's defectors to McCain is likely to decrease after Democrats choose a nominee and the focus shifts to defeating the Republican nominee.

Gallup analysts also noted that voters tend to threaten party desertion but don't necessarily do so. A recent Gallup survey found that 11 percent of Republican voters said they would vote for a different party or not at all if McCain doesn't pick a running mate who is more conservative than he is.

Historically, the party-switch factor has shown to be less dramatic, Gallup analysts said. Less than 10 percent of Republicans and Democrats crossed party lines in pre-election Gallup polls from 1992 to 2004.

Still, when almost three out of 10 Clinton supporters say they would vote for McCain over Obama, it suggests that divisions are running deep within the Democratic Party.

If the fight for the party's nomination were to continue until the convention in Denver in late August, the Democratic Party could suffer some damage as it tries to regroup for the November general election.

In the second poll, Rasmussen Reports found that 87 percent of all voters - and 85 percent of Democrats - believe it is 'somewhat likely' that both Clinton and Obama will remain in the race until the convention.

Fifty-two percent of Democrats said it is 'very likely' the nomination won't be decided until the convention.

The Rasmussen poll also found that there's equal dislike on either side of the Democratic race for the rival candidate: 22 percent of both Clinton and Obama supporters said they believe the other candidate should drop out of the race.