Lisa Nandy has broken ranks to become the first Cabinet minister to join Andy Burnham on the campaign trail in Makerfield. The Culture Secretary accompanied the Mayor of Greater Manchester as he canvassed voters in the Wigan constituency, where he is hoping to win a by-election on June 18. The sight of one of Sir Keir Starmer’s senior ministers campaigning with a likely leadership challenger will be seen as an embarrassment for the Prime Minister. Mr Burnham failed to say on Saturday that he had confidence in Sir Keir. Sharing a photograph of herself with Mr Burnham and other Labour activists, Ms Nandy said on X: “Good to be out on the doors in Winstanley today and lovely to see some good friends come over to help. “Life has been too tough for people in this borough for too long, but we are determined to turn this around.” Ms Nandy failed to explicitly back Sir Keir after last week’s historic local election defeat and acknowledged that many Labour campaigners were “hurting”.…