Hillary Clinton, the former first lady who lost the race for the Democratic presidential nomination this year, has praised Sarah Palin's achievement in becoming the first female Republican vice-presidential candidate.

Clinton told a Democratic campaign rally in Florida on Monday that the Alaska governor's candidacy as John McCain's running-mate was a "great accomplishment".

However, Clinton, campaigning for former rival Barack Obama, the Democratic candidate, and Joe Biden, his running-mate, said McCain and Palin "are not the change that we need".

The New York senator also said the election would be decided on issues, rather than the historical significance of the candidates.

"Women as well as men make their decisions after they weigh the evidence," Clinton said.

It was Clinton's second campaign visit to Florida since she conceded the Democratic nomination to Obama in June.

Palin factor

Palin, meanwhile, attended a ceremony in Detroit on Monday, where she and McCain picked up an endorsement from the Fraternal Order of Police Union.

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She has been governor since 2006 and her previous public service was as the mayor of a small town.

But her nomination has energised the Republican campaign and about 6,000 people turned up to see McCain and Palin at a rally in Albuquerque on Saturday.

Five public opinion polls released on Monday said McCain and Obama were tied as they headed into the final eight weeks of the race for the White House.