The article linked below says it all far better than I can. It is by the nation's leading authority on the Constitution, Laurence Tribe of Harvard Law School.
I would only add two things.
(1) As long as the GOP in Congress think they can get their agenda done with Trump, they will keep him in power. They will also not dump him if he is still popular with the GOP voters. Last week 85% of GOP voters viewed him favorably. This was prior to his firing Comey. Though his rating with Independents is slipping, it's the GOP voters in next year's primaries who are of concern to incumbent GOP Congress members up for re-election. If GOP voters continue to like Trump, GOP candidates will be scared to go against him.
(2) Trump should also be impeached for his stupidity. As I pointed out in my two previous postings, he has been stupid and ignorant enough to blatantly commit obstruction of justice and then own up to it even after his staff hasd concocted a cover story that might have saved him. We can't have this stupid, ignorant egomaniac as president.
Please read this piece: Trump must be impeached. Here’s why.