Sir Keir Starmer is facing the worst crisis of his leadership. A coordinated cabinet revolt has plunged Westminster into chaos. Sources inside Downing Street describe a prime minister shaken but defiant.

The rebellion began in secret. It was planned over WhatsApp and encrypted Signal groups. The ringleaders included senior ministers who once backed Starmer. They now believe he is leading Labour to electoral disaster.

“He’s too cautious,” one cabinet minister told me. “We can’t win on a platform of managed decline.” The main grievance is Starmer’s refusal to adopt bold economic policies. His shadow chancellor, Rachel Reeves, has insisted on fiscal discipline. The rebels want higher public spending and tax rises on the wealthy.

The revolt went public on Tuesday. A leak to a Sunday newspaper revealed a letter signed by 12 cabinet members. It demanded an emergency meeting to discuss “the direction of travel”. Starmer was blindsided. His aides spent hours trying to contain the damage.

“We knew there was discontent,” a senior No 10 official said. “But this scale was unexpected.” The letter’s signatories include the Education Secretary, the Health Secretary, and two former leadership rivals. They argue that Labour’s poll lead is fragile. A single scandal could wipe it out.

The trigger was a private dinner at the home of a wealthy donor. Starmer attended along with several shadow cabinet members. Reports emerged that he promised not to raise top rates of income tax. The rebels saw this as a betrayal. Labour’s base expects redistribution. Starmer’s triangulation angers them.

Angela Rayner, the deputy leader, is believed to be sympathetic to the rebels. But she has not signed the letter. Her office says she is “focused on the campaign”. Friends hint she could be a unity candidate if Starmer falls.

Starmer called an emergency cabinet meeting on Wednesday. It was tense. One participant described it as “a funeral”. Starmer defended his strategy. He pointed to Labour’s 20-point lead in the polls. He warned that civil war would hand the election to the Tories.

“He was pretty tough,” a minister present told me. “He said those who can’t get behind him should leave.” No one walked out. But the meeting did not heal the rift. The rebels are digging in. They plan to table a motion of no confidence at the next parliamentary party meeting.

Starmer’s allies dismiss the revolt as a “storm in a teacup”. They note that Labour is still ahead. But the numbers tell a different story. Internal polling shows Starmer’s personal ratings are sinking. Voters cannot articulate what he stands for.

The irony is that Starmer has delivered party unity. He has purged antisemitism. He has restored credibility. But he has not offered a compelling vision. The public want change. Starmer offers competence.

“Competence isn’t enough,” another rebel said. “We need to inspire. He doesn’t.” The revolt has exposed a deeper problem. Labour is a coalition of social democrats and centrists. Starmer has tried to straddle both. Now the coalition is fracturing.

The Conservative Party is watching with glee. They have pounced on the chaos. Boris Johnson tweeted: “Starmer can’t control his own party. He can’t control the country.” The attack line is simple: Labour is divided and unfit.

Starmer’s allies accuse the rebels of vanity and impatience. They point out that Tony Blair faced similar revolts. He ignored them and won landslides. But Blair had charisma. Starmer does not.

The next 48 hours are critical. The rebels are demanding Starmer commit to higher taxes on the rich and a major Green new deal. They want an emergency budget. Starmer is expected to resist. He believes the economy will recover and that the Tories will implode. He wants to stay on the high ground.

“If he gives in, he loses control,” a party strategist said. “If he doesn’t, he faces a leadership challenge.” The stakes could not be higher. The election is due in 2024. Labour cannot afford a long civil war.

But the rebels are not backing down. They believe Starmer is a liability. One source said: “We’d rather lose with someone who fought for what we believe in than win with someone who stood for nothing.”