Sen. Joe Manchin, D-W.Va., told Fox News Tuesday both sides in the Senate impeachment trial of President Trump have been very hypocritical in relation to their views of the impeachment of President Bill Clinton more than two decades ago.

Manchin told "Your World" on Tuesday that he takes his Senate oath of impartiality seriously and believes any further witnesses that could provide information germane to President Trump's trial should be heard from.

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"I don't know how I go home to West Virginia and explain that I had to make a decision in a trial, the most important thing that I have ever done or will ever do as an elected official, an impeachment of the president of the United States, without having all the evidence and all the witnesses that had the knowledge," Manchin told host Neil Cavuto.

"Whoever is pertinent to the charges against the president should be the ones that should be considered," he added after Cavuto noted that former National Security Adviser John Bolton and Acting White House Chief of Staff Mick Mulvaney have been floated as figures who senators have said could be helpful. Many Republicans have also called for testimony from Rep. Adam Schiff, D-Calif., and Hunter Biden if Democrats are able to call Bolton or Mulvaney.

"I'm a proud West Virginian and I'm a proud American," Manchin said. "It doesn't matter whether you are Democrat or Republican -- do the right thing and make sure you have the evidence and all the witnesses that can help you make an important decision."

Manchin added that it has been difficult to explain to the "hypocrisy" of both sides to his constituents.

"They have all reversed their position 180 degrees," he said, singling out Trump legal representatives Alan Dershowitz and Kenneth Starr, as well as Sen. Charles Schumer, D-N.Y.

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In 1999, Starr was the independent counsel investigating Clinton over the "Whitewater" land deal in Arkansas. That probe uncovered the Monica Lewinsky scandal. Schumer defended Clinton against calls to impeach him from Republicans like then-House Speaker Newt Gingrich of Georgia and then-House Judiciary Committee Chairman Henry Hyde of Illinois.

"I'm sure the framers, the brilliant people they were, did not have that much wiggle room and you could change your position in a 10- or 20-year period for something they wrote that has been holding for 200 years, something just doesn't resonate to me," Manchin said.

Manchin also called former New York City Mayor Rudy Giuliani a "rogue proxy" for Trump, adding that no president should have a figure like that negotiating or involved in state-related affairs overseas.