This is 'the fight over impeachment': Ex-federal prosecutor breaks down why Trump pressuring McGahn raises the stakes

In light of the news that President Donald Trump pressured former White House Counsel Don McGahn to say publicly that the president did not obstruct justice, former federal prosecutor Renato Mariotti broke down the implications of the news.

Specifically, Mariotti said in a lengthy Twitter thread, the episode suggests Trump knew McGahn is one of the most important witnesses in any potential obstruction of justice-related impeachment proceeding, and wanted him to head off his own utility to House Democrats — and that the whole situation underscores why Democrats are so keen to get McGahn's testimony and interviews with special counsel Robert Mueller: