The Republican National Convention opened Monday — but just barely, with all major speeches and festivities delayed for a day as Tropical Storm Isaac lightly lashed this waterfront city.

Even the brief opening festivities — a quick proclamation by Republican National Committee Chairman Reince Priebus, an opening prayer and a short video featuring presidential candidate Mitt Romney — were overshadowed by concerns that Isaac is on a collision course toward the northern Gulf Coast on the anniversary of Hurricane Katrina.

The disrupted schedule had leading Republicans questioning whether a four-day convention is still necessary — and left thousands of delegates unexpectedly at loose ends for the day.

Rain was interspersed with periods of sun. Some delegates even went to the beach.

Republicans officials said late Monday that they would press ahead with Tuesday’s full schedule, including the convention’s keynote address by New Jersey Gov. Chris Christie, a major speech by Ann Romney and a roll call vote that will formally nominate Romney as the party’s presidential nominee.

But officials continued to closely monitor Isaac, which forecasts predict will make landfall on the Gulf Coast, potentially near New Orleans, late Tuesday or early Wednesday.

The decision to move ahead without changes carried significant risk for the GOP. The image of Republicans partying in Tampa while Gulf Coast residents face a potentially deadly storm could be damaging, particularly given the coincidence of the Katrina anniversary. The 2005 hurricane took more than 1,836 lives, and the George W. Bush administration was widely criticized for the government’s handling of the disaster, especially the actions of the Federal Emergency Management Agency and its director at the time, Michael Brown.

“Obviously, our thoughts are with the people in the path of the storm,” Romney strategist Russ Schriefer told reporters Monday. “We hope that they’re spared any major destruction, and we’re thinking about them,”

Based on evening forecasts, Schriefer said organizers did not see a need for speakers to tone down their partisan rhetoric. “I think this is a good debate, a healthy debate and an important debate. It’s a debate the American people have been looking forward to,” he said.

With a new Washington Post/ABC News poll showing the presidential race essentially tied, Republicans face an additional challenge: amplifying their message that Romney would make a better steward of the economy while competing for the country’s attention during a large and potentially damaging storm.

Several network news anchors decamped from Tampa for New Orleans on Monday, presenting the GOP with the uncomfortable prospect of split-screen coverage of the convention and the storm on Tuesday and Wednesday, while President Obama manages storm response.

Vice President Biden already had canceled a campaign trip to Florida because of the storm, and Obama led a call with governors in Gulf states late Monday. Obama did not, however, cancel the start of his own two-day campaign swing Tuesday in Iowa, Colorado and Virginia.

Romney plans to fly to Tampa on Tuesday, his campaign said. Aides said he spent Monday practicing his convention speech at Brewster Academy, a school near his Wolfeboro, N.H., lake home. He is set to formally accept his party’s nomination on Thursday.

As the storm moved north, a squall of a different kind appeared possible on Tuesday, as delegates who supported Texas Rep. Ron Paul for president over Romney said they would object to the adoption of party rules they believe are intended to make it harder for grassroots activists to challenge the party establishment.

A group of Paul supporters held forth on the convention floor after the 71 / 2-minute official opening. Some held Paul signs emblazoned with the words, “We can do better,” a campaign theme.

“We can do better than Romney,” said John Honey, 37, an alternate delegate from Arkansas. “Romney may beat Obama. Paul definitely would.”

Any floor squabble over rules could be embarrassing for Republicans already starting the convention late.

With the four-day schedule crunched into three days, some leading Republicans questioned whether future conventions will just be scheduled for three days. Democrats have planned for months for a three-day convention in Charlotte, N.C., next week.

“I’m not sure that having a four-day convention, for the future, makes a lot of sense,” said House Speaker John A. Boehner at a luncheon Monday hosted by the Christian Science Monitor.

Former Nevada Gov. Robert List, a convention delegate, said the disruption by Isaac only emphasizes that party conventions need to be shorter.

And he said the storm might end up helping the Republicans by showcasing GOP governors in the midst of crisis in states such as Florida, Alabama and Louisiana. The storm has also drawn more attention, he said, to the gathering in Tampa.

“We may reap a little audience as a consequence,” List said.

Priebus defended the weekend decision to delay Monday’s events, even though the storm tracked farther west than had been predicted and largely spared Tampa from major weather troubles.

“I mean, you have to make the call days before today,” he said on NBC’s Today. “We have to err on the side of safety. There’s just no way around it.”

Around Tampa, delegates, who suddenly found themselves with a less crowded scheduled than anticipated, tried to fill a newly quiet day.

“The fact is, you’re expecting to just jump right into the convention,” said Beverly Gossage, a delegate from Kansas, after attending a session of Newt Gingrich’s “Newt U” at a Hyatt near the convention site.

On Monday, though, she couldn’t: Gossage said her delegation had to scramble to find its own transportation, since the regular shuttles they expected weren’t running. They showed up in the middle of the Gingrich session, missing the introduction.

Mary Rose Spano, a delegate from Scranton, Pa., said she was disappointed to arrive and find the day’s events canceled for a weather disaster that never came. But she said she didn’t blame the convention’s organizers.

At noon on Monday, she was asked: What next?

“We’re going to go back and maybe see what else we can find out. . . . Basically, we’re going to go back to our hotel,” she said.

David A. Fahrenthold, Laura Vozzella, Kevin Merida, Karen Tumulty, Philip Rucker in Wolfeboro, N.H., and Felicia Sonmez in Milwaukee contributed to this report.