John McCain and his fellow Republicans rallied behind vice presidential pick Sarah Palin on Tuesday and attacked Democrat Barack Obama at a convention featuring a reduced role for President George W. Bush.
Republicans will nominate Mr McCain and Ms Palin as their candidates this week to face Obama and running mate Joe Biden in the November 4 US presidential election.
On the first night of convention speeches, after a delay due to Hurricane Gustav, police used pepper spray and teargas to drive protesters away from the downtown Xcel Energy Centre where the event was being held.
The confrontation followed a peaceful march on behalf of poor people by more than 1,000 demonstrators.
Ms 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.
Some have questioned Mr McCain's judgment in picking Ms Palin, 44, and how thoroughly the relatively unknown first-term governor's background was examined before her selection last week.
"When he takes office next January, John will have an outstanding leader at his side. America will have a strong and principled vice president in the governor of the great state of Alaska, Sarah Palin," Mr Bush said in a brief speech broadcast to the convention from the White House.
Former Tennessee Republican Senator Fred Thompson blasted "Washington pundits and media big shots" who had been critical of Ms Palin and launched an attack on Mr Obama as "the most liberal, most inexperienced nominee to ever run for President".
"Let's be clear ... the selection of Governor Palin has the other side and their friends in the media in a state of panic. She is a courageous, successful reformer who is not afraid to take on the establishment," he said.
Comparing Ms Palin to Mr Obama without mentioning the Democrat's name, Mr Thompson said she "has actually governed rather than just talked a good game on the Sunday talk shows and hit the Washington cocktail circuit".
Mr Bush, the toast of the 2000 and 2004 conventions who has since seen his approval ratings sink to about 30 per cent, stayed in Washington for this one to monitor hurricane relief. Mr Bush praised Mr McCain, his rival in a bitter primary election fight eight years ago.
"He's not afraid to tell you when he disagrees. Believe me, I know," said Mr Bush, who has had an uneasy relationship with Mr McCain over the years.
Mr Thompson promoted McCain's foreign policy expertise and said it was far more expansive than Mr Obama's, citing Mr Obama's speech before 200,000 cheering Germans in Berlin in July.
There was every indication Mr McCain and other Republicans would stand by only the second woman ever picked as a major party's vice presidential nominee, despite the hubbub.
Republicans like her anti-abortion, pro-guns stances and her history of government reform in Alaska in her two years as governor.
Mr McCain's aides prepared Ms Palin for a speech to the convention, expected early this morning, during which she will accept the nomination. The presidential candidate predicted a warm welcome for Ms Palin when she addresses the convention on Wednesday night. "America's excited and they're going to be even more excited once they see her," Mr McCain told reporters in Cleveland.
Analysits said Mr McCain wanted to create some buzz with his pick of Ms Palin as his running mate - but not this kind of buzz.
In choosing a politically unknown first-term Alaska governor as his No. 2, Mr McCain invited an exploration of her past and her public record - including an ongoing ethics probe into the firing of a public safety official in Alaska and news that her unmarried teenage daughter is pregnant.
"Clearly they would rather not be talking about state trooper investigations and teenage pregnancies right now," said Dan Schnur, one of Mr McCain's aide during his 2000 presidential bid who now heads the Jesse Unruh Institute of Politics in California.
Many Republicans rallied around Ms Palin after the news of her daughter's pregnancy surfaced on Monday, and leading social conservatives dismissed the issue as a private matter and praised the family's choice to deliver the baby.
Scenarios for Sarah Palin candidacy
Potential scenarios for Sara Palin candidacy and its impact on the November 4 presidential election against Democratic presidential candidate Barack Obama and his No. 2, Joe Biden.
The choice of Ms Palin, 44, a conservative abortion rights opponent with a record of bucking the Republican establishment in Alaska, has rallied the conservative base to Mr McCain, who has struggled to win over that crucial constituency. Her speech will give the party a chance to answer questions about her familiarity with domestic and foreign policy issues, and possibly address the issue of her 17-year-old daughter's pregnancy and the investigation into whether she abused her power in having a public safety commissioner fired in Alaska.
The selection of the political unknown has raised questions about Mr McCain's judgment and the degree to which his campaign investigated Ms Palin's background. That is a distraction that could hurt the campaign's efforts to generate momentum for the election battle with Mr Obama. "My vetting process was completely thorough and I'm grateful for the results," Mr McCain told reporters in Philadelphia.
Ms Palin's slot on the ticket is secure, but new revelations or scandals from Alaska could threaten her standing. It would take a lot, however, to dump her two months before the election.