Republicans convened a throttled-back national convention Monday to nominate John McCain as president, substituting celebrations for fundraising efforts as the party that was hammered for ineptitude during Hurricane Katrina three years ago rallied to support U.S. Gulf Coast voters affected by Hurricane Gustav.

Convention talk also focused on an announcement that the 17-year-old, unmarried daughter of McCain's running mate, Alaska Gov. Sarah Palin, was pregnant -- a disclosure the campaign said was aimed at rebutting Internet rumors that Palin's son, born last April, was actually that of her daughter.

McCain and his fellow Republicans set aside partisan politics and festivities planned for the convention opening, adopting a more a subdued business-only tone in deference to Gulf Coast residents who braced for the worst as the hurricane, diminished to a category 2 storm, rammed ashore along Louisiana and drove inland. The storm dropped to a category 1 Monday afternoon, but was still packing 90 mph (145 kph) winds.

President George W. Bush and Vice President Dick Cheney had been scheduled to speak a the convention Monday night, but canceled because of the storm. Instead, first lady Laura Bush and Cindy McCain were making back-to-back appearances separated by videotaped messages from the governors of Texas, Mississippi, Alabama and Florida -- states likely to feel effects of the storm. The convention is to conclude Thursday night with McCain formally accepting the party nomination.

Gustav blasted into the Louisiana coast southwest of New Orleans about three years to the day after Hurricane Katrina roared through the same area, inundating the famed city, killing at least 1,600 people in the region and leaving the Republican Bush administration permanently stained for its lackadaisical handling of that storm.

At an emergency operations center in Austin, Texas, Bush said he wanted to ensure that assets were in place to handle the storm, and that preparations were being made to help the Gulf Coast recover.

"The coordination on this storm is a lot better than on -- than during Katrina," Bush said. "It was clearly a spirit of sharing assets, of listening to somebody's problems and saying, `How can we best address them?"'

He lauded Gulf Coast residents who heeded warnings to evacuate.

Democrats also swung their attention to the storm.

Presidential nominee Barack Obama urged hundreds of thousands of supporters to donate to the Red Cross to help victims of Gustav. In a mass e-mailing, he urged supporters to "please give whatever you can afford, even $10, to make sure the American Red Cross has the resources to help those in the path of this storm."

Obama scaled back a speech on Monday's U.S. Labor Day holiday in Detroit to keep attention on the Gulf Coast. After stops in Michigan and Wisconsin, he was returning to his Chicago headquarters to monitor the storm's progress and decide his schedule for the rest of the week.

Gustav denied McCain the first of four intensely partisan days of intense and national news coverage that generally brings a boost in the polls. Obama's poll numbers rose after what was generally regarded as a successful Democratic National Convention last week.

But in scaling down the convention and focusing on the storm, McCain can also highlight leadership skills and provide a contrast to Bush's slow response to Katrina -- at a time that Democrats emphasize McCain's links to the Bush presidency.

McCain was in the Midwestern state of Ohio on Monday. He visited a disaster relief center in the town of Waterville, where he helped pack cleaning supplies and other items into plastic buckets that will be sent to the Gulf Coast area.

McCain said that while there is now better coordination among federal, state and local authorities, there are still problems such as not enough communication equipment or search-and-rescue capabilities.

"It's not perfect, but I think that it's dramatically different than it was in response to Katrina," McCain said in an interview broadcast on NBC television.

The suspense over Gustav had temporarily taken the spotlight off Palin, a relative unknown at the national level who was just announced as McCain's running mate on Friday.

She is seen as a maverick reformer in geographically huge but sparsely populated Alaska, is deeply conservative and avidly opposed to abortion -- a key issue for the Republican evangelical base. The 44-year-old carried the last of her five children to term knowing the fetus had Down syndrome.

But Palin and her husband announced in a statement on Monday that their unmarried 17-year-old daughter Bristol is pregnant, and would marry the father of her child. McCain adviser Mark Salter said the announcement was meant to rebut Internet rumors that the governor's youngest son, born in April, was actually born to Bristol.

Obama condemned campaign rumors involving the children of candidates. Speaking Monday to reporters in Michigan, he said, "I think people's families are off limits, and people's children are especially off limits."

Obama adamantly rejected any suggestion that his campaign helped spread the rumors. "Our people were not involved in any way in this, and they will not be."

The risks for McCain lay in Palin's lack of experience. She is in her first term as Alaska's governor, having served before that as mayor of Wasilla, a small community of about 6,500 not far north of Anchorage. McCain has consistently attacked the experience of the 47-year-old Obama, a first-term U.S. senator who previously served eight years in the Illinois state legislature.

Meanwhile, on the streets of St. Paul, protesters smashed windows, punctured car tires and threw bottles during an anti-war march to the convention site. Police used pepper spray in confrontations with demonstrators and arrested five.

Instead of the single coherent march that organizers had hoped for, fringe groups of anarchists and others wrought havoc along the streets between the state Capitol and the Xcel Energy Center where the convention was taking place.

Police estimates of the crowd shifted during the event before settling on 8,000 to 10,000. The crowd was clearly in the thousands, many of them marching peacefully.