Just when Labour thought it had corked the bottle of internal dissent with a by-election campaign, the bubbles of anxiety about Sir Keir Starmer have fizzed right back up. The prime minister's Defence Investment Plan (DIP) was meant to showcase direction and delivery - instead, it's become the latest exhibit in the case against his ability to get things done.

Defence Secretary John Healey resigned on Thursday, declaring that the proposed military spending "falls well short" of what's needed. His replacement, Dan Jarvis - a veteran of Northern Ireland, Kosovo, Iraq, and Afghanistan - now has the unenviable task of explaining this embarrassment to NATO defence ministers next week. Adding to the chaos, armed forces minister Al Carns did television interviews while still a minister, saying "my job is to steady the ship," only to jump off the ship and resign an hour later. Carns had earlier told this reporter that if a leadership contest starts, "I'm not scared of gunfire."

Surveying this mess are potential leadership challengers Andy Burnham, Wes Streeting, and Carns himself. Downing Street and the Treasury, bruised and winded, maintain they were doggedly trying to find a defence deal they could sell to the armed forces, the government, and the country. They failed on the first, struggled on the second, and haven't even gotten to the third. Starmer's allies insist he's wrestling with fiendish trade-offs: a sluggish economy, high taxes, growing benefits bills, and a dangerous world demanding huge defence spending. Other departments had already been told to expect cuts to fund the military. The Conservatives say welfare must be slashed. Starmer now must pick himself up yet again and make the case for his flailing premiership - a task that seems to get harder by the hour.