Sen. Mark Warner said Sunday that allegations against Democratic Maine Senate candidate Graham Platner will be up to voters to weigh, but are “disturbing” if true.

“I do think at the end of the day American voters will make those decisions, and I don’t know Mr. Platner. I’ve never met him,” Warner, D-Va., told ABC News’ “This Week” co-anchor Martha Raddatz. “I would just say this: The allegations are made. I think you ought to have at least some attempt to … disprove them, if that’s the case.”

Last week, the New York Times published a story based on interviews with several of Platner’s ex-partners, one of whom described his behavior at times as “unsettling” and “reckless.” Some of the women interviewed for the article claimed that Platner could be demeaning to women and one woman alleged he was physically rough with her. Others described him more positively, with one calling him a “gentle giant.”

Platner has said he struggled with PTSD and self-medicated with alcohol. He acknowledged he has been a “bad boyfriend” but denied any physical roughness with past partners.

Platner is hoping to face Sen. Susan Collins in November, a long-time Republican incumbent who has over-performed in her past elections. To win control of the Senate, defeating Collins is key for Democrats, some of whom fear that Platner’s controversies could cost them the race.

While Warner said he wished both parties would hold themselves to a higher standard, he pointed out that President Donald Trump faced multiple controversies when running for president in 2016 and still was elected.

“This whole realm changed dramatically when Donald Trump ran his first time, was caught on tape saying extraordinarily dispiriting things,” Warner said. “That seemed not to stop Trump getting elected.”

This is a developing story. Please check back for updates.