Don't count "Real Time" host Bill Maher as an enthusiastic passenger on the Joe Biden train for 2020 just yet.

The liberal Maher expressed concerns on Friday's show about Biden's viability as a White House contender, telling the "Real Time" panel he has "mixed feelings" about the former vice president's candidacy.

"I do worry, I do worry," Maher said about Biden. "Like I've said about age, it's individual. Some people look pretty good ... Joe doesn't look good. He looks like he's on a coin."

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But Maher acknowledged he'll be "all in" for Biden if the Democrat proves to be the only candidate capable of defeating President Trump in 2020.

The HBO star then referred to Biden's recent interaction with a 10-year-old girl on the campaign trail, an encounter that raised eyebrows when Biden told her, "I'll bet you're as bright as you are good-looking." Biden had previously faced criticism for remarks and gestures toward girls and women.

"I worry he's going to say that two days before the election," Maher said.

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Panelist Lawrence Wilkerson -- a retired U.S. Army colonel and former chief of staff to former Secretary of State Colin Powell -- then compared Biden to former President George H.W. Bush, who was accused by multiple women of inappropriate grabbing in his final years, and recalled his own interactions with Biden, telling the panel Biden would say and do things that were "utterly weird."

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Axios reporter Jonathan Swan reminded Maher how early it is in the 2020 election process, recalling how former Republican Govs. Jeb Bush and Scott Walker were seen as frontrunners in 2016 before businessman Donald Trump entered the race.