London CNN  — 

Boris Johnson has just taken an enormous gamble.

After a rebel alliance of British lawmakers seized control of Parliament in order to push through a bill blocking no-deal Brexit, the UK Prime Minister took the extraordinary step of firing 21 members of his own party who backed the measure.

And he made good on threats he would seek a general election, tabling a motion that called for a vote mid-October.

Taken together, the strategy is a massive risk – it detonates his parliamentary majority and pushes the House of Commons to agree an election that he has no guarantee of winning.

But there are still quite a few hurdles – and risks – for Johnson to contend with before the UK gets its third general election in less than five years.

Could Johnson split the Conservative party?

Rebels on Johnson’s side had been forewarned that voting in favor of the emergency no-deal legislation on Tuesday would result in their being thrown out of the parliamentary party and barred from standing as a Conservative at any future election.

But the unprecedented move to sack 21 Conservatives, many of them long-serving members, was a stark sign of just how high the stakes have been ratcheted up. Some observers suggest it could even amount to a reshaping of the party itself.

The Conservatives are one of the most successful political parties in the world, at least in part because it has been a broad church of people who are economic, social, and liberal conservatives.

The expulsion of senior moderate members, including figures like Father of the House Kenneth Clarke – who has been in politics longer than some MPs have been alive – and Winston Churchill’s grandson, Nicholas Soames, is a signal that the center of gravity in the Conservative Party is shifting.

Clarke said as much on the BBC’s Newsnight program: “Anyone who who comes up to me and tells me I’m not a Conservative is taking an odd political view. It’s the Brexit Party rebadged.”

Boris Johnson delivers a speech at Downing Street on the eve of a tumultuous day in Parliament.

In carrying out the cull, Johnson blew apart his majority, presumably with the idea of replacing those members in a general election with others who will toe that line.

By calling for a snap election, he could in fact be aiming to increase his majority and strengthen his hand on Brexit all at the same time. That said, his predecessor Theresa May tried the same tactic in 2017 – and it spectacularly blew up in her face.

Tim Bale, professor of politics at Queen Mary, University of London, says it’s hard to see it going the same way this time.

“As Theresa May found in 2017, you can’t necessarily make the election about what you want it to be about … the risk is that [opposition Labour Party leader] Jeremy Corbyn manages to pull off the trick he did last time and come back from a long way behind to deny the Conservative Party a majority,” Bale said.

“But Corbyn might not be able to pull off the same trick twice, a lot of the reason that he did well last time was because of Theresa May and the fact that she is a poor campaigner.”

Labour aside, Johnson still face risks from other factions should an election go ahead. It’s almost a certainty that the party will lose many of its seats in Scotland, which it will have to make up somewhere else. And the Liberal Democrats are strong enough in areas that voted Remain in 2016 that they may well grab a few seats off the Conservatives and eat into the Tory haul. The Brexit Party led by Nigel Farage could also be in a position to pick off some Conservative votes if the UK still hasn’t left the EU by the time of the vote.

Who decides if there’s an election?

Under the Fixed-term Parliaments Act (FTPA), Johnson can’t just schedule an election. First, he must get the support of two-thirds of lawmakers in the House of Commons.

And that means getting the support of the opposition Labour Party.

Pro-EU supporters protest outside Parliament on Tuesday.

Labour Party leader Jeremy Corbyn has been demanding an election for months. So he would find it hard to oppose one now. But Labour is suspicious of Johnson’s motives.

Corbyn opposes a general election that would cross over the October 31 Brexit deadline, resulting in the UK crashing outin the runup to the vote.

While Johnson may promise to abide by the proposed mid-October timeframe, it’s within his gift to change the date at the last minute.

“Corbyn has said again and again that Labour wants a general election, ‘bring it on’… but they are in a slightly awkward position,” said Professor Tony Travers, director of the Institute of Public Affairs at the London School of Economics. “Labour will be wary of giving Johnson an unlimited choice of running an election when it suits him.”

And Labour has been less than enthusiastic about the prospect of a snap election, given they’re not doing very well in opinion polls, Travers added.

Still, Corbyn seemed to relish having the ball in his court Tuesday, saying if the Prime Minister wanted an election, the rebel-backed bill blocking no-deal would need to be passed first.

“He wants to table a motion for a general election, fine,” Corbyn said. “Get the bill through first in order to take no deal off the table.”

What if Johnson doesn’t get an election?

If his election bid fails and the bill to block a no-deal is backed, Johnson will be in a bind. Would he do the one thing he has said he never would – seek an extension to the Brexit process?

“If legislation goes through to stop a no-deal and Johnson can’t figure a way to a general election, then he’s in a very difficult position… he’s got little choice but to go back on his word and try to make the case for a deal with the EU,” Travers said.

Still, it may not make a difference for Johnson, seemingly the ultimate Teflon politician. “Given what’s slid off him before I don’t think it would be a career-terminating event, especially if he has been forced to do it by parliament. If that does happen, he can fight a general election on a hard Brexit platform and have a few months in which to try a better deal with the EU… or get us back into the same spot we’re in today,” Bale said.

“It is a gamble, but then you have to think about what are the other options and they don’t look that great either. It is a risk, but it is probably a risk worth taking.”