After a career trying to keep the U.S. Supreme Court above politics, Justice Stephen Breyer’s retirement underscores just how central the court now is to the U.S. political wars.

Breyer’s White House announcement Thursday was timed perfectly to give President Joe Biden a needed chance to change the national conversation and reinforce the court’s beleaguered liberal wing.

It comes amid a seismic Supreme Court shift driven by a Republican agenda. The court now has a 6-3 conservative majority that could be poised to overturn the constitutional right to abortion, abolish the use of race in university admissions and slash the Environmental Protection Agency’s power to combat climate change.