DAVIE (CBS4) – Florida Senator Bill Nelson is known as a moderate in the Senate. But at his only debate with Republican Congressman Connie Mack, Nelson pulled no punches, accusing Mack of being a congressional no show.

“Why don’t you explain how you don’t show up for work?” Nelson asked Mack during their one and only debate at Nova Southeastern University in Davie Wednesday. “You have one of the worst voting records in Congress. And when you do show up for work it’s even worse.”

Mack defended his voting record, saying Nelson has missed many votes in Washington himself. The Southwest Florida Congressman blasted Nelson for supporting President Barack Obama’s health care reform law, cutting Medicare Advantage for Florida seniors, raising taxes and increasing regulations on business.

“The people of Florida of you saying one thing to them and then voting with Barack Obama,” Mack said.

“Is that the only line you have memorized,” Nelson countered.

Mack, 45, son of former Florida Senator Connie Mack III, is tying his campaign to the top of the GOP ticket.

“Mitt Romney needs another Republican as senator from Florida,” he said.

Nelson, 70, is seeking his third term in the Senate. He has consistently led Mack in the polls.

Nelson’s campaign has turned down more debates before Election Day.