ST. PAUL, Minnesota: Senator John McCain and his advisers decided to halt all but the most essential activities for the Republican National Convention, sacrificing a major televised platform for McCain's political message as he sought to project a forceful response to the threat of Hurricane Gustav. With the storm expected to hit the U.S. Gulf Coast on Monday, McCain and his team spoke by phone on Sunday morning and, one participant said, quickly decided that there was no choice but to cancel much of the first day of the convention. McCain advisers said the programming for the rest of the four-day convention would be determined on a day-to-day basis. Many questions remained open, such as whether McCain and his running mate, Governor Sarah Palin of Alaska, would appear in St. Paul to accept their party's nominations, or would appear by video from the Gulf Coast. On Sunday afternoon, McCain declared on television that this was a time for members of his party to "take off our Republican hats and put on our American hats." He made similar remarks at a campaign rally in St. Louis, Missouri, even as some of his allies there, like former Governor Mitt Romney of Massachusetts and Senator Christopher Bond of Missouri, publicly criticized Democrats and their nominee, Senator Barack Obama, at the same event. "This is a time when we have to do away with our party politics, and we have to act as Americans," McCain said in St. Louis after a brief tour, with Palin, of a U.S. government disaster relief center in Jackson, Mississippi. Convention planners and delegates in St. Paul said, and McCain advisers acknowledged, that it could be politically perilous to continue the convention as the Gulf Coast braces for the arrival of Hurricane Gustav. The Bush administration's unsteady response to Hurricane Katrina, which left New Orleans in ruins three years ago, outraged Americans, drew criticism from McCain and remains, for many, a stain on President George W. Bush's record. In St. Paul, the McCain campaign chartered a plane to fly a dozen members of the Louisiana delegation home and created a Gulf states briefing committee, made up of top Republican officials from the region. Party organizers, meanwhile, considered whether to tamp down the celebrations, although events for major donors and delegate parties were going ahead Sunday night. Democrats who gathered here to counter the Republican message canceled a gathering with reporters Sunday and said they would determine each day how to calibrate the tone of their activities. Rick Davis, the McCain-Palin campaign manager, said at a news conference here that the Monday convention session would be scaled back to open at 3 p.m. and probably end by 5:30 p.m. It will be limited to official business like adopting the platform and electing convention officers. At least one night of speakers and guaranteed news coverage will be lost, something Davis alluded to only obliquely, saying the campaign had obviously hoped it could have "a more traditional" convention. "Events have conspired to do otherwise," said Davis, adding later when pressed that "we really don't have the luxury of trying to evaluate the politics of this kind of situation." As McCain traveled to Mississippi on Sunday, Obama decided to monitor the approach of the hurricane from afar. Obama was briefed on the evacuation in a telephone call with Michael Chertoff, the secretary of homeland security, on Sunday afternoon, as well as conversations with the Louisiana governor, the New Orleans mayor and other officials. Obama told reporters that he might visit the Gulf Coast after "things have settled down." He and his advisers discussed making a weekend trip to the region, but they concluded that visiting the area before the storm would complicate the efforts of the authorities there. When Obama asked how he could help, Governor Bobby Jindal of Louisiana, a Republican, told Obama that he could help amplify the message of the mandatory evacuation, particularly among the black residents of New Orleans. So on Sunday morning, Obama conducted telephone interviews with four New Orleans television stations and one radio station, lending his voice to those who were warning residents to heed the evacuation order. After Hurricane Katrina, Obama introduced legislation in the Senate requiring officials take specific steps to evacuate the elderly and the disadvantaged. In his call with Chertoff on Sunday, aides said, Obama asked whether the new evacuation plan was being followed. Obama said his campaign would mobilize its e-mail list of supporters, to volunteer or send contributions, as soon as the impact of Hurricane Gustav became known. "We can activate an e-mail list of a couple million people who want to give back," Obama told reporters after services at St. Luke's Lutheran Church in Lima, Ohio. "I think we can get tons of volunteers to travel down there if it becomes necessary." Asked whether he believed it was appropriate for McCain to travel to the Gulf Coast, Obama said: "A big storm like this raises bipartisan concerns, and I think for John to want to find out what's going on is fine." McCain also urged Americans to donate their time and money as needed. He made the decision to halt some convention activities during a conference call Sunday morning. The potential for disaster along the Gulf Coast has not only overshadowed the Republicans this weekend but also has diverted media attention from both the Democrats' glow over their convention in Denver last week and their criticism and questioning of Palin, whom McCain introduced as his running mate Friday. The major television networks are pulling some of their top talent out of Minnesota, promising to diminish, if not upend, coverage of the convention. Katie Couric will head to the Gulf Coast to open the "CBS Evening News" from there Monday night, instead of from the convention hall as planned. Charles Gibson of ABC News and Brian Williams of NBC are expected to do the same. Michael Luo and Jim Rutenberg contributed reporting from St. Paul, Minnesota, Michael Cooper from St. Louis, Missouri, and Jeff Zeleny from Toledo, Ohio.