ST. PAUL (Reuters) - John McCain and his fellow Republicans rallied behind his vice presidential pick, Sarah Palin, on Tuesday and his campaign accused Democrat Barack Obama of sexism for questioning her level of experience.

The support came as the Republican convention to nominate McCain and Palin as the party’s candidates was finally getting started, after a delay due to Hurricane Gustav, with President George W. Bush to speak via satellite hookup.

Palin’s disclosure that her unmarried 17-year-old daughter is pregnant and the news that she had hired a private lawyer in an ethics probe in Alaska have triggered a media firestorm and led some to question McCain’s judgment and how thoroughly the relatively unknown governor’s background was examined before she was selected last week.

In excerpts of his remarks, Bush cited McCain’s national security experience as justification for electing him on November 4 over Democrat Barack Obama.

And he backed Palin on a day Palin was behind closed doors in St. Paul preparing for an address she will give to the convention on Wednesday.

The McCain camp issued a photo of Palin meeting Bush’s wife, Laura, and McCain’s wife, Cindy.

“When the debates have ended, and all the ads have run, and it is time to vote, Americans will look closely at the judgment, the experience, and the policies of the candidates -- and they will cast their ballots for the McCain-Palin ticket,” Bush said.

McCain predicted a warm welcome for Palin when she addressed the convention. “America’s excited and they’re going to be even more excited once they see her tomorrow night,” McCain told reporters in Cleveland. “I’m very, very proud of the impression that she’s made on all of America and I’m looking forward to serving with her.”

In Philadelphia, he defended his search. “My vetting process was completely thorough and I’m grateful for the results,” McCain said.

SEXISM?

McCain’s campaign fought back hard after Obama told CNN on Monday that Palin’s level of experience as a former mayor of tiny Wasilla, Alaska, did not match his own, citing the size of his campaign.

“My understanding is that Gov. Palin’s town, Wasilla, has I think 50 employees. We’ve got 2,500 in this campaign. I think their budget is maybe $12 million dollars a year -- we have a budget of about three times that just for the month,” Obama had said.

McCain adviser Carly Fiorina accused him of sexism, a charge the Obama camp faced during Democrat Hillary Clinton’s primary battle against him.

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“The facts are that Sarah Palin has made more executive decisions as a mayor and governor than Barack Obama has made in his life,” Fiorina said.

“Because of Hillary Clinton’s historic run for the presidency and the treatment she received, American women are more highly tuned than ever to recognize and decry sexism in all its forms. They will not tolerate sexist treatment of Gov. Palin,” Fiorina said.

The McCain campaign released a copy of Palin’s Republican voter registration card to rebut a report in The New York Times that Palin was a member of the Alaskan Independence Party for two years in the 1990s. The group has sought a vote on whether the state should secede from the United States.

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“The allegations that Gov. Palin was a member of (the) Alaska Independence Party are false. She’s never been a member of the Alaska Independence Party,” said McCain spokesman Brian Rogers.

When Palin was announced on Friday, Republicans welcomed her entry into the presidential race against Obama and Joe Biden in the November 4 election as bringing a burst of energy to the McCain campaign.

They like her anti-abortion, pro-guns stances and her history of government reform in Alaska in her two years as governor.

There was every indication McCain and other Republicans would stand by only the second woman ever picked as a major party’s vice presidential nominee, despite the hubbub.

“He absolutely keeps her,” said Larry Sabato, a political science professor at the University of Virginia. “If he drops her, the election is over. There’s zero chance that he’ll drop her.”

Bush was the headliner among Tuesday’s speakers, who also included former Sen. Fred Thompson, who lost to McCain in the Republican primaries, and close McCain ally Sen. Joe Lieberman, a Democrat-turned-independent from Connecticut.

McCain campaign manager Rick Davis said the timing of Palin’s speech was not yet set. He would not comment on whether she would use it to address any of the controversies surrounding her.

But her remarks will be “the most important speech the nominee will give in the course of the election” because of the large television audience, he said.