Story highlights King predicted the GOP would stay unified and get through all of Trump's Cabinet choices

"I don't know if it (sexism) was directly the cause, but you can't avoid the conclusion," King said

Washington (CNN) Republicans made a "terrible" mistake in shutting down Sen. Elizabeth Warren on the Senate floor, Sen. Angus King said Wednesday night, adding that the decision gave the appearance of sexism.

The Maine senator who caucuses with Democrats told CNN's Erin Burnett on "OutFront" that his colleagues had made an unfair and ill-conceived decision to invoke a rarely used Senate rule barring Warren from debate over President Donald Trump's pick for attorney general, Jeff Sessions.

As for the question of whether or not Warren, a Massachusetts Democrat, was right to try reading a letter from Coretta Scott King criticizing Sessions, he called it a "close call."

King said the incident would likely lead to a fundraising bonanza for Democrats, saying he thought it was "a terrible mistake" by Republicans. He also said he understood accusations of sexism over the incident.

"I don't know if it (sexism) was directly the cause, but you can't avoid the conclusion," King said.

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