"The Senate, what is it like a French work week? You get, like, three days where you have to show up? You can campaign or just resign and let someone else take the job," Bush said. "There are a lot of people living paycheck-to-paycheck in Florida and they are looking for a senator who is willing to fight for them."
Rubio's voting record — or lack thereof — has been an issue the presidential hopeful has been dealing with since launching his campaign.
According to Govtrack.us, Rubio has missed 12.3 percent of the Senate's roll-call votes from January 2011 to October 2015, well above the 1.6 percent median among current senators.
"Over the last few weeks, I've listened to Jeb as he has campaigned across the country and he said he was modeling his campaign after John McCain," Rubio retorted to Bush. "You know how many votes John McCain lost when he was carrying out that furious comeback that you're now modeling under?"
"I don't remember you ever complaining about John McCain's vote record, and the only reason you're complaining about mine is because somebody ... has convinced you that attacking me is going to help you," Rubio said.
Watch our live coverage here or weigh in on the debate here.