A Republican senator raised eyebrows this morning by declining to say whether President Trump would be re-nominated by the GOP in the 2020 presidential election.

Sen. Susan Collins (R-Maine), who wrote in Paul Ryan last November rather than vote for Trump, made the statement in an interview in Bangor, Maine, with MSNBC's Hallie Jackson.

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Collins was asked about what it might take for Republicans to stop supporting Trump. 

"Do you think he will end up the party's nominee?" Jackson asked. 

"It's too difficult to say," Collins answered. 

Her comment came after a discussion about Trump's response to the deadly Charlottesville white supremacist riots.

She said President Trump "wavered back and forth" on condemning neo-Nazis and his statements "failed to meet the standard" of leadership of the office.

Collins opposed Trump and most of her Senate colleagues on repealing ObamaCare, maintaining that the replacement proposals were not good enough. 

She was joined by Republicans John McCain and Lisa Murkowski in voting with Democrats to block the repeal a few weeks ago. 

Other Republicans have been highly critical of Trump in recent weeks, with Sen. Bob Corker (R-Tenn.) going as far as to question Trump's "stability" and "competence" after Charlottesville.

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