Labour’s leadership rivals are due to clash at a debate but the bitterest battle has been taking place in a dustier setting – the courts.
The Court of Appeal is due to hear a case on Thursday that could mean hundreds of thousands more votes for Jeremy Corbyn – or the loss of them.
The legal tussle can be traced back to Corbyn’s grassroots movement and the decision of the party’s National Executive Committee.
Since Corbyn took over as Labour leader, the party has swelled with new recruits, mostly believed to be loyal to him.
When setting out the rules for the leadership contest, the NEC introduced a six-month cut off point designed to stop more recent joiners from automatically getting a vote. Instead, they would have to pay £25 to get one.
Defenders of the decision say this rewards longstanding party members and prevents entryism. Critics say it freezes out enthusiastic new recruits who may not be able to afford a high fee.
A group of new members decided to get the argument settled in court, and on Monday, the High Court ruled in their favour.
According to the BBC, the decision adds between 126,592 and 150,000 more voters to the franchise.
But the Labour party decided to appeal. The case will be heard on Thursday morning, although a decision may take longer to reach.
If the Labour party wins it, these supporters could once again find themselves unable to vote, which could be a boost for Corbyn’s rival Owen Smith.
Nevertheless, it will be hard for Labour’s anti-Corbynites to shake the criticism that rather than letting members decide, the party establishment has resorted to desperate measures.