Labour Lords are planning a vote of no confidence in Jeremy Corbyn over antisemitism in the Labour Party.
The peers are due to hold an emergency meeting on Monday to discuss the idea, with the potential vote held over Tuesday and Wednesday.
It the vote is passed it would have no formal effect but would be a major blow to the authority of the Labour leader.
A Labour source told the Guardian it would be “both undemocratic and absurd for unelected peers with no mandate to seek to remove an elected leader who twice won the landslide support of Labour’s membership and led Labour to the biggest increase in the party’s vote since 1945”.