A Republican U.S. Senate candidate, whose controversial remarks on rape and abortion prompted party leaders to urge him to drop his bid, has reaffirmed plans to stay in the race.

Representative Todd Akin said Friday he is continuing his run for a Senate seat in the state of Missouri. In a news conference, he said he would soon resume campaign events.

Earlier this month, Akin started a firestorm of controversy when he defended his opposition to abortion — even in cases of rape — by saying that victims of what he called “legitimate rape” had a natural mechanism to avoid pregnancy.

He later apologized, but Republican leaders, including presumptive presidential nominee Mitt Romney, urged him to drop out of the race.

Meanwhile, Mr. Romney drew heated criticism from President Barack Obama's campaign, Friday, after he joked about whether Mr. Obama was born in the United States.

During a campaign rally in Michigan, Mr. Romney quipped that no one had ever asked to see his birth certificate. The remark prompted a swift response from the Obama campaign, which accused Mr. Romney of embracing the “most strident voices in his party, instead of standing up to them.”

Some conservative activists have continued to question whether Mr. Obama was born in the U.S., although the president released his birth certificate last year.

Mr. Obama had no campaign appearances on Friday and was set to travel to the Camp David presidential retreat later in the day.

Meanwhile, organizers of next week's Republican National Convention in Tampa, Florida, are keeping a close eye on a tropical storm churning in the Caribbean.

Weather forecasters say Tropical Storm Isaac could reach Florida just as the convention is getting underway.