While Keir Starmer’s authority as prime minister feels terminally undermined after calls from MPs and departing ministers to step down, he remains inside No 10 – for now. So how, and when, might he be removed? Here are some possible scenarios. 1. A contest without Burnham The Greater Manchester mayor, Andy Burnham, the probable favourite among Labour MPs, is not in parliament. Any resolution in the coming weeks would require a sitting MP to trigger a contest by getting the backing of 80-plus colleagues, or persuading Starmer to set a timetable to quit. The MP for Makerfield in Greater Manchester, Josh Simons, announced on Thursday afternoon that he was giving up his seat and wanted Burnham to take it. It remains to be seen if Downing Street will let Burnham stand, and if it does, whether he would win. If that does not happen for any reason, then there could be an impasse.…