Recently, Robert Mueller's team has announced that Paul Manafort has violated his plea arrangement. Unbeknownst to Mueller, Manafort's lawyers were sharing vital pieces of information with President Trump's legal team.
Brent Budowsky of The Hill outlined how pardoning Manafort could be an impeachable act:
Paul Manafort’s betrayal and double-dealing against Robert Mueller and his special counsel team appears to be a desperate ploy designed to achieve a presidential pardon, which will fail because Trump’s attorneys will advise him in ways similar to what I wrote here.
I have long believed that the case for obstruction of justice involving efforts to impede the Mueller investigation is far stronger, based on publicly known evidence than our public discussion would suggest.
Additionally, I would assert that while a president can lawfully pardon almost anyone, for almost any crime, a pardon could also be crucial evidence in support of an obstruction of justice case, and potentially an additional count in an obstruction of justice case.
If a pardon is offered to influence a witness in a criminal investigation, that pardon could indeed be a crime. There has been evidence that earlier in the case, Trump’s lawyers discussed a pardon with Manafort’s lawyers.
If Trump does pardon Manafort, the public firestorm of anger and outrage would be so extreme that impeachment consideration would probably be initiated even by a Republican House, and certainly by a Democratic House in January.