WEST DES MOINES, Iowa — Sen. Marco Rubio, R-Fla., says he has little concern about Donald Trump's debate plans.

Prior to a Tuesday town hall in West Des Moines, Rubio told Sean Hannity that Trump's absence could spell more speaking time for other candidates.

The Florida senator echoed familiar refrains about bringing unity to the Republican Party while attracting new voters and did not take any direct hits at his GOP opponents. He also fielded questions about the ongoing investigation into Hillary Clinton's private email use, his tax policy and his faith.

Rubio told a member of a pipe fitter union that he had no quarrels with unions and criticized President Obama for hurting blue collar workers with burdensome regulations. He did praise unions for offering assistance and job training for veterans.

When asked what he would do with NASA, Rubio pledged to "reinvigorate the space program," arguing it is not only an incubator for American innovation but essential to national security.

The senator also spoke extensively about his faith and how it informs his decision-making.

"My faith is Christianity and you can't impose that on anybody," said Rubio. "People better hope my faith influences me, just like it's influenced our country."

Despite trailing in early voting states, Rubio feels the increased fire he is taking from his fellow GOP candidates shows the strength of his campaign.

"When you go caucus, we must choose a nominee that wins," Rubio urged caucus-goers. "I will win. They know it and they attack me more than any other Republican in this field."

Rubio noted how former Florida Gov. Jeb Bush is spending nearly $1 million a day attacking him.

"In a way it's good," Rubio told Hannity. "You don't attack someone if they are not doing well."