The longest-serving Senate leader had been widely expected to retire at the end of his current term. He made it official on his 83rd birthday, after a recent run of opposing President Trump’s nominees.

The onetime GOP leader is known for brass-knuckled partisanship in pushing through conservative policy and his tangles with President Trump.

The Kentucky Republican has served more than 40 years in the chamber, and became one of the most consequential and divisive legislators in recent history.