A Democrat-backed judge has won a key seat on the Wisconsin Supreme Court, in a vote widely seen as a referendum on Donald Trump’s administration.

Susan Crawford overcame the wrath of the US president and a $21 million (£16 million) donation to her Republican opponent by Elon Musk in the most expensive judicial election in American history.

Her win is a boost for the Democrats, who were quick to celebrate her victory as a triumph over the billionaire Tesla owner after framing the race around his and Mr Trump’s popularity.

Following Ms Crawford’s win, Kamala Harris gloated about her party beating an “unelected billionaire” in the state she lost to Mr Trump in the 2024 election.

The party’s candidate in a separate Florida congressional race lost, however, but closed the gap by almost half from the previous election.

In Wisconsin, Ms Crawford defeated Brad Schimel, a former Republican attorney and conservative judge from Waukesha county, after Mr Musk helped fund the most expensive judicial contest in American history.