(CNN) The first week of impeachment public hearings was devastating for President Donald Trump. The House Intelligence Committee heard testimony from foreign service officials deeply troubled by the administration's shadow policymaking cabal, headed by Rudy Giuliani, that withheld vital foreign aid in exchange for campaign support.

The week ended with former Ukraine Ambassador Marie Yovanovitch recounting the vicious smear campaign that helped lead to her being drummed out of her job. As she spoke, the President confirmed his willingness to attack her this way via live tweets.

Julian Zelizer

As if that were not bad enough, David Holmes, an aide to the top US diplomat in Ukraine, William Taylor, ended the day behind closed doors explaining , according to his opening statement, how he overheard the President speaking loudly on the phone with Ambassador Gordon Sondland in a restaurant in Kiev about the investigations related to Hunter Biden and conspiracy theories about the origins of the Russia investigation.

In other words, everyone has been confirming the report of the whistleblower. Republicans have been left to offer faux complaints about the process and to suggest that all of the bad things that are being reported are based on hearsay.

We have no idea how the impeachment process will turn out. Any good student of history realizes just how uncertain the politics of impeachment can be. Solid predictions often turn out to be untrue. Republicans would always stand by Richard Nixon, or so the experts said in January 1974, until they no longer did. While we are most likely looking at the House voting in favor of several articles of impeachment against President Trump and the Senate voting to let President Trump remain in office, things can change quickly.

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