My first thought is a moderate Republican Never Trumper, since support for the impeachment of Nixon and Clinton was fairly common among moderate Republicans, but I think some Democrats could also be consistently pro-impeachment. Joe Lieberman voted to acquit Clinton (and thus doesn't count), but is a high-profile example of a Democrat who was critical of Clinton's behavior. One individual who actually did support the Clinton and Trump impeachments is
Paul McHale, the Democratic congressman who represented the Lehigh Valley for most of the 1990s.
“There were those who in 1998, particularly some political supporters, who could not understand that it’s essential that as a constitutional duty, the House must hold every president accountable, regardless of party affiliation,” McHale said. “As a result of my belief that that is the constitutional duty of the House, I lost some friends.”...
While he sharply rebukes Clinton’s actions that led to impeachment, McHale views President Trump’s actions as even starker, describing Clinton’s lying under oath as paling in comparison to Trump’s withholding security aid as he urged the Ukrainian leaders to conduct investigations involving Democrats.
“The president put his own political interest ahead of our country’s security,” McHale said. “It’s hard to imagine an offense that would be more egregious under the Constitution.”
