In their final U.S. Senate debate, Republican candidate Mel Martinez (search) and his Democratic rival, Betty Castor (search), clashed over the war in Iraq and the minimum wage, underscoring the nature of a hotly contested campaign.

With undecided votes hanging in the balance, both candidates find themselves in a deadlock as they try to succeed retiring Democratic Sen. Bob Graham (search). The contest also is considered one of the top races that could help decide control of the Senate.

Martinez, a former member of President Bush's Cabinet, said he backed the president's decision to enter Iraq, challenging recent comments made by Castor that she would not vote to approve the war resolution -- "knowing what I know now" -- because weapons of mass destruction have not been discovered there.

"She does not believe in the mission," Martinez said in Monday's debate, adding: "At the end of the day, we need a United States Senator who is resolute, who is unflinching in the face of terror."

But the former state education commissioner said she resented the suggestion that her opponent "keeps trying to build the case that I will not be" unflinching.

The debate was held at Florida International University and aired on CBS affiliates around the state. Polls have showed Castor and Martinez virtually tied.

Castor criticized Martinez's opposition to a proposed statewide increase to the minimum wage, saying the attorney favors "tax breaks for the wealthiest Americans, for millionaires," over low wage workers.

Martinez, however, recalled walking door-to-door trying to earn spending money after fleeing Cuba as a teenager. He said that raising the minimum wage to $6.15 an hour would hurt the state's economy.

"When the minimum wage goes up and it is imposed by government, unfortunately, there will be fewer jobs available," Martinez said.

Asked by reporters later, Martinez said "no one can work at $11,000 per year and feed a family. It just doesn't happen and adding another dollar an hour does not change the circumstances."

On the day that the country learned that U.S. Supreme Court Chief Justice William H. Rehnquist has thyroid cancer, the candidates tangled over the selection of federal judges.

Martinez, former U.S. Housing secretary, said Castor would rely on a "litmus test" in selecting judicial nominees, and urged an end to "gridlock in the Senate" over appointments.

"There he goes again, saying something that is not accurate about my position," Castor countered, saying she would seek "highly qualified" judges.

The candidates renewed their long-standing debate over Castor's handling of suspected terrorist Sami Al-Arian while she served as president of the University of South Florida. Castor placed the professor on paid administrative leave but Martinez has said she did not do enough to rid the campus of Al-Arian and his associates.

Castor said she was the only person who took action against Al-Arian, noting that President Bush met with the suspect during a 2000 campaign stop in Florida.

On Social Security, Martinez sought to buffer criticism from Castor that he favors privatization and "risky schemes." He said he wants to give young workers the option of investing their funds in private accounts. Looking directly into the camera, Martinez said: "I am rock solid in support of our Social Security system."

Castor and Martinez said they supported Florida's ban on gay adoptions, but were at odds over a proposed constitutional amendment banning gay marriages. Martinez said marriage should be between a man and a woman and the initiative would stymie "activist judges." Castor said she opposed the amendment, calling it was divisive.

On the administration's new rules restricting travel to Cuba, Martinez said the goal was to end Fidel Castro's regime.

"My opponent says I'm not for the Cuban family," said Martinez, who is trying to become the first Cuban-American in the Senate. "The biggest enemy for the Cuban family is Fidel Castro."

Castor said the United States should have a "humanitarian" approach to travel to the communist island and said the Bush administration's policy "doesn't just hurt Fidel Castro, it hurts Cuban families."