Sen. Joe Manchin, D-W.Va., said Wednesday morning that Democrats were wrong to sit sullenly for most of President Trump's State of the Union address, and said that mild protest showed a lack of respect to the presidency.

"I was very, very upset when I saw the Republicans never, ever stood up with Barack Obama, and there was things I didn't agree about President Obama in his speech," he said on MSNBC.

"But I was taught in West Virginia there's a little bit of respect, and you should show that. And I did that then, and I did it last night," he added.

"I think the Democrats were wrong in not showing respect," Manchin said. "That's just me."

Manchin has been known to support Trump's efforts to support coal, and is seen as a Democrat who can be swayed on some issues. But he also it's the "wrong idea" for Trump to approve the release of a Republican memo that purportedly outlines surveillance abuses by the FBI.

Trump told a lawmaker on the way out of the House chamber, after his State of the Union speech, that he would release it "100 percent."