The Republican-controlled Wisconsin Senate voted Thursday to fire the battleground state’s nonpartisan top elections official, prompting a legal challenge from Democrats who say the vote was illegitimate.

Democratic Attorney General Josh Kaul said in a lawsuit that Senate Republicans don’t have the authority to oust Wisconsin Elections Commission Administrator Meagan Wolfe and accused them of attacking the state’s elections.

It’s the latest in a whirlwind of deep partisan divisions in Wisconsin, where Republicans who control the Legislature are threatening to impeach a newly elected Supreme Court justice before she’s even heard a case. They’re also floating plans to overhaul the state’s electoral maps before the high court can toss out current boundaries that favor the GOP.