British Prime Minister Boris Johnson sparked angry talk of a “coup” Wednesday after he moved to shut down Parliament for several weeks in an extraordinary effort to silence rebel lawmakers and ram through Britain’s departure from the European Union.

The decision to shutter the legislature for more than a month, starting no later than Sept. 12, stifled dissenters as the days ticked toward Britain’s most momentous deadline in generations. Outraged lawmakers said it concentrates power in Johnson’s hands and sharply curtails their ability to thwart a no-deal Brexit. Some spoke of a constitutional crisis.

It also suggested that Johnson’s bumbling exterior conceals a ruthless tactician, ready to exploit any opening to bring about the split from the E.U. and consolidate power.

Absent a delay, Britain will leave the European Union on Oct. 31.

If it leaves without a transition deal, analysts say, the country could face food and fuel shortages. The economic turmoil could spread to the E.U. nations, which collectively are the United States’ biggest trading partner. Many observers fear that with a hardened border, fresh violence could flare in Northern Ireland. And because President Trump has embraced Brexit and Johnson, the break with Europe would become a major test of the White House’s skepticism of multilateral institutions and trade blocs.

In Brussels, diplomats said they are increasingly convinced that Johnson will pilot Britain off the cliff without the safety net of a deal. European lawmakers expressed astonishment that he would so brazenly tie the hands of Parliament, in which a majority opposes a no-deal Brexit.

The Conservative prime minister denied claims that ­Brexit is the reason he sought the new timetable, telling reporters he wants a new session of Parliament so he can lay out the government’s “very exciting agenda.”

He added that there would be “ample time” for lawmakers to debate Brexit.

But few in Britain, even among Johnson’s allies, accepted his explanation of why he had decided to ask Queen Elizabeth II to ­“prorogue” — or suspend — Parliament. The queen, who is on holiday at her Scottish estate of Balmoral, approved the request, as is customary.

A “constitutional outrage,” John Bercow, speaker of the House of Commons, said in a statement. “However it is dressed up, it is blindingly obvious that the purpose of prorogation now would be to stop Parliament debating Brexit and performing its duty.”

Proroguing Parliament is not unheard of — it happens most years in connection with the queen’s speech, often in May or June. But the five-week gap this time is the longest break since 1945. Recent suspensions have been measured in days, not weeks. 

Johnson told reporters he asked the queen to give her usual annual speech outlining the country’s legislative agenda in mid-October, effectively suspending Parliament between Sept. 11 and Oct. 14. 

The British pound swooned nearly 1 percent against the euro after the announcement before recovering slightly.

Labour Party leader Jeremy Corbyn promised to fight the move.

“Boris Johnson’s attempt to suspend parliament to avoid scrutiny of his plans for a reckless No Deal Brexit is an outrage and a threat to our democracy,” he wrote on Twitter. “Labour will work across Parliament to hold the government to account and prevent a disastrous No Deal.”

The controversy drew the attention of Trump, who has gravitated toward Johnson as a fellow nationalist and goaded Britain to be more aggressive about Brexit. Trump and Johnson met over the weekend at the Group of Seven summit in Biarritz, France.

“Would be very hard for Jeremy Corbyn, the leader of Britain’s Labour Party, to seek a no-confidence vote,” Trump wrote on Twitter. “Boris is exactly what the U.K. has been looking for, & will prove to be ‘a great one!’ ” 

Opposition leaders had talked earlier about forcing a vote of no confidence in Johnson’s government sometime before late October. Wednesday’s maneuver, if successful, would drastically narrow their window to next week or immediately before Britain drops out of the bloc.

They could also try to pass a law mandating that Johnson seek a Brexit delay.

But given how badly the opposition forces are fractured, it is unclear whether they have the votes for either option. And they have precious little time.

“Unless MPs come together to stop him next week, today will go down in history as a dark one indeed for UK democracy,” tweeted Nicola Sturgeon, leader of the Scottish National Party.

In the rest of the European Union, leaders are bracing for Britain to leave without a deal. But there was anger — and some shock — that it could apparently happen with minimal input from Parliament.

“We could see a no-deal Brexit coming. Now it’s a no-debate Brexit that’s looming,” tweeted Nathalie Loiseau, a member of the European Parliament and an ally of French President Emmanuel Macron. “What disease is British democracy suffering from to fear a debate before making one of the most important decisions in its history?”

German lawmaker Norbert Röttgen, an ally of German Chancellor Angela Merkel tweeted: “How does respect for democracy go together with suspending parliament?!”

A petition launched on the British Parliament’s website calling for the government not to suspend the body quickly exceeded 100,000 signatures, the number needed for it to be considered for a parliamentary debate. The tally neared 1 million Wednesday night and was rocketing skyward, although any such debate would not lead to legislative action.

Johnson’s move infuriated some Conservative lawmakers who have sought to avoid a no-deal Brexit.

“This is pretty unprecedented,” said Dominic Grieve, a Conservative lawmaker. He described it as “tantamount to a coup.” 

Grieve said he would consider voting against his own party if a no-confidence vote is called.

Johnson appears to be gambling that those who are against a no-deal exit won’t be able to organize quickly enough to mount an effective opposition.

“By using the political devices at hand, Boris has compressed everything into such a tight window that those who want to block a no-deal Brexit have a mountain of a task,” said Scott Lucas, a politics expert at the University of Birmingham, adding that he believed Wednesday’s move “sharply” increased the chance of a no-deal withdrawal.

Many observers say Johnson is ramping up for a possible early general election, which he says he doesn’t want. At present, he has a working majority of just one. Even if he loses a confidence vote, it is not clear that Corbyn or anyone else would be able to form an alternative government, and Johnson could campaign in a new election on a staunch anti-E.U. platform, analysts said. He faces pressure from both flanks because the Brexit Party has been growing its support.

During a week of negotiations with other E.U. leaders, including over the weekend at the G-7 summit, Johnson left his counterparts feeling that he would prefer to exit with a deal, according to officials briefed on the conversations who spoke on the condition of anonymity to discuss private assessments.

But leaders including Macron and German Chancellor Angela Merkel felt Johnson was ready to depart on the October deadline if no politically feasible deal materializes in the meantime, senior officials said. 

Short-circuiting debate on ­Brexit could push lawmakers, even skeptics, to vote for any new deal Johnson comes up with, just to avoid a no-deal departure.

But the officials said they think Johnson was setting an impossible task by demanding changes to the deal that would cross E.U. red lines, and they pegged the chances of a fresh compromise as low. 

Birnbaum reported from Brussels. Jennifer Hassan in London and Quentin Ariès in Brussels contributed to this report.