TAMPA, Fla. – His Republican National Convention curtailed by a threatened hurricane, Mitt Romney conceded Sunday that fresh controversy over rape and abortion is harming his party and he accused Democrats of trying to exploit it for political gain.

“It really is sad, isn’t it, with all the issues that America faces, for the Obama campaign to continue to stoop to such a low level,” said Romney, struggling to sharpen the presidential election focus instead on a weak economy and 8.3 percent national unemployment.

His comments came as aides and party officials hurriedly rewrote the script for the convention, cut from four days to three because of the threat posed by approaching Tropical Storm Isaac. The storm is forecast to gain hurricane strength as it churns through the Gulf of Mexico but to pass well west of the convention city.

The revised schedule included a symbolic 10-minute session Monday in a nearly empty hall, during which officials intend to launch a debt clock set to zero. The objective is to show how much the government borrows throughout the week.

Officials did not rule out further changes because of the weather, and sidestepped when asked what might happen if, as seemed possible, the storm made landfall in the New Orleans area on the seventh anniversary of Hurricane Katrina. That storm killed 1,800 people and devastated the city.

“We’re 100 percent full steam ahead on Tuesday,” said Reince Priebus, chairman of the Republican National Committee, expressing confidence the one-day delay would be the extent of the cancellations.

Despite concerns about the weather, a mammoth pre-convention celebration went on as planned Sunday night, attended by thousands of delegates and others who flocked to the Rays major league baseball stadium turned into a party venue in nearby St. Petersburg.

Priebus said Romney’s nomination will take place Tuesday, as will approval of a conservative party platform.

The former Massachusetts governor delivers his acceptance speech Thursday night before a prime-time TV audience, then sets out on the final leg of a quest for the presidency that spans two campaigns and more than five years.

For all the Republican attempts to make the election a referendum on the incumbent’s handling of the economy, other events have intervened.

An incendiary comment more than a week ago by Rep. Todd Akin, the party’s candidate for a Senate seat in Missouri, is among the intrusions. In an interview, he said a woman’s body has a way of preventing pregnancy in the case of a “legitimate rape.” The claim is unsupported by medical evidence, and the congressman quickly apologized.

Romney and other party officials, recognizing a political threat, unsuccessfully sought to persuade Akin to quit the race. Democrats have latched on to the controversy, noting not only what Akin said but also his opposition to abortion in all cases.

“Now, Akin’s choice of words isn’t the real issue here. The real issue is a Republican Party — led by Mitt Romney and Paul Ryan — whose policies on women and their health are dangerously wrong,” said a recent letter from Debbie Wasserman Schultz, the chairwoman of the Democratic Party.

The party also posted a Web video that emphasizes the Republican Party’s opposition to abortion and digitally alters the Republicans’ “Romney-Ryan” logo to say “Romney Ryan Akin.”

Interviewed on Fox, his comments broadcast Sunday, Romney said the controversy over Akin “hurts our party and I think is damaging to women.”

Delegates marked time as the storm raked the Florida Keys en route to a projected landfall along the Gulf Coast.

Romney said he was concerned for the safety of those who “are going to be affected” by the storm, which is predicted to worsen into a hurricane as it heads for land.