Sen. Mitch McConnell has announced he won’t seek reelection next year, ending a decadeslong tenure as a power broker who championed conservative causes but ultimately ceded ground to the fierce populism of President Donald 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.

Mitch McConnell announced the impending close of his four-decade Senate career Thursday, underscoring a remarkable legacy of turning American government rightward but also capping a fading era in Republican politics.