Announcing the high-stakes move, Burnham said he wanted to return as an MP because "much bigger change is needed at a national level".

The by-election in Makerfield -- which sits within the Greater Manchester city-region that Burham has led as mayor since 2017 -- will only happen because its current Labour MP announced Thursday he was resigning.

"I am standing aside so that Andy Burnham can return to his home, fight to re-enter Parliament, and if elected, drive the change our country is crying out for," outgoing lawmaker Josh Simons said.

Labour's National Executive Committee (NEC), which selects the party's candidates, blocked Burnham from standing in another by-election earlier this year.

If it accepted him this time, it would trigger an election for the Manchester mayoralty, which the party could struggle to retain based on disastrous local and regional elections for Labour last week.

But Nigel Farage, leader of the anti-immigration Reform UK which topped last week's contests, said the party will "throw absolutely everything" at the vote.