WASHINGTON (AP) — Justice Anthony Kennedy’s retirement is setting off a momentous confirmation battle for President Donald Trump’s next Supreme Court nominee that is certain to consume the Senate, inflame partisan tensions and shape the outcome of the midterm elections.

All sides quickly mobilized Wednesday after Kennedy — a singular voice on the court whose votes have decided issues on abortion, affirmative action, gay rights, guns, campaign finance and voting rights — sent shockwaves through Washington by announcing his retirement plans. Trump said he would start the effort to replace Kennedy “immediately” and would pick from a list of 25 names that he updated last year. Senate Majority Leader Mitch McConnell declared that the Senate “will vote to confirm Justice Kennedy’s successor this fall.”