Wes Streeting quit as Health Secretary on 20 May, telling the BBC he had lost confidence in Prime Minister Keir Starmer.

Streeting was one of Starmer's most senior ministers. His resignation is the biggest cabinet departure since Labour won the election last year.

The timing matters. In May, Labour suffered heavy losses in local council elections across the country. This sparked a serious revolt among Labour MPs, with some publicly calling for Starmer to go. The BBC reported on 14 May that Starmer was fighting hard to keep his job.

Streeting had already made his next move clear. On 16 May, he told the BBC he would enter any Labour leadership contest if one happened. Once he said that, staying as Health Secretary became impossible — he could not lead the health service while positioning himself to replace the PM.

Here is what this means for Starmer. Whenever a prime minister faces a leadership challenge, senior ministers face a choice: stay in your job and hope the boss survives, or leave the cabinet and enter the contest. The longer the uncertainty drags on, the more ministers think leaving is safer. Streeting's departure makes it easier for others to follow.

The next question is whether enough Labour MPs will formally challenge Starmer. Party rules allow MPs to force a confidence vote if enough of them sign up to it. This has historically been harder to achieve than Westminster gossip suggests. Starmer's team will be counting votes carefully.

What makes this difficult for Starmer is that Streeting was not just any minister. He was the cabinet's leading voice on NHS reform and one of the government's best performers in television interviews. The new Health Secretary inherits a massive job: the NHS in England spends around £180 billion per year, and is permanently in the headlines over waiting lists and A&E delays. Voters care about these numbers far more than they care about internal Labour politics. That fact is actually Starmer's best defence — a government torn apart by itself cannot fix the NHS.

The electoral backdrop is difficult for Starmer. Labour won the 2024 election on a low share of the overall vote. This gave the party a large majority, but one built on shallow support. The May council losses gave Starmer's critics ammunition: they can argue that the current leadership cannot rebuild public support before the next election. Streeting's statement that he had lost confidence in Starmer, rather than disagreeing on NHS policy, keeps the focus on this question.

Starmer has faced worse and survived. Prime ministers can weather cabinet departures if they can show they are still in control of parliament and have a credible plan to reset policy. The coming days will show whether Starmer can project enough authority to stop more ministers quitting — and whether he can persuade wavering MPs that changing leadership again, so soon after the election, is riskier than staying put.

Streeting himself would be a credible leadership candidate if the party votes on a new leader. He is seen as someone from the modernising wing of Labour, comfortable with economic policy. He spent three years arguing the NHS needed structural change, not just more money. He does have real support among Labour MPs. Whether it would be enough to win a party election is harder to say.