At times Marco Rubio was, well, robotic. And Patrick Murphy was dazed by a punch.

Both instances in Monday night's U.S. Senate debate came courtesy of Donald Trump.

Rubio knew he would face questions about Trump and was prepared to distance himself from him — repeatedly, without giving an inch to Hillary Clinton. Some examples:

• "I don't trust either one of them."

• "Horrifying choice America has in this election cycle."

• "Not the most inspirational choice we've ever had in America history."

• "A disturbing choice."

• "A difficult and less than ideal choice."

• "Two deeply flawed candidates."

Rubio also repeatedly invoked the dodge "God willing" when asked if he would serve a full six-year term if re-elected and not run for president in 2020, as is widely assumed should Clinton win.

"Just a clarification, are you promising to fill all six years of your term?" moderator Jonathan Karl asked.

"I'm going to serve in the Senate for the next six years, God willing," Rubio replied. "And let me tell you, not only am I going to serve in the Senate over the next six years, we are going to get a lot done, God willing, over the next six years."

So this means you are not running for president?

"I'm going to be a senator for the next six years on behalf of the state of Florida. You can't be a senator or president at the same time. I am running for the U.S. Senate, I'm going to serve six year, God willing."

Murphy, trailing in the polls and facing eroding financial support from national Democrats, hit his message points, implying Rubio is hostile to women on reproductive rights and other issues, while painting an overall picture that his rival supports the lewd behavior of Trump. So Rubio went for a counterpunch, noting that several years ago, a photo was posted on Facebook showing Murphy "groping a woman."

"That's inappropriate behavior!" Rubio said of the photo, which appeared to show Murphy's hand on the woman's breast.

Murphy's flustered response: "Let's just talk about Donald Trump again, right?"

The 33-year-old Democrat spent part of Tuesday trying to explain the photo, saying it was from his 20s and he and his girlfriend were at dinner. "Look, when Donald Trump goes low, Marco Rubio goes lower," Murphy told reporters in West Tampa.

Times staff writer Tony Marrero contributed to this report.