Boris Johnson could become Britain's shortest-serving Prime Minister if he calls and loses a snap election to end a power struggle with parliament over a potential no-deal Brexit.

But the odds remained in his favour, dipping slightly, after a defeat in the Commons on Wednesday when MPs voted through a bill that forces him to ask the EU to delay Brexit until January 31, unless he has a deal approved by parliament beforehand on the terms of the exit.

Watch: How did the legislation to delay Brexit get through parliament?

According to Oddschecker, Johnson's Conservative party on Thursday had a 2/5 predicted chance of winning the most seats in parliament if snap elections were called, which is an equivalent percentage chance of just over 71%.

This is down from 1/3 odds (75%) on Tuesday.

The main opposition Labour Party's chances, however, have increased — on Tuesday they stood at 4/1 (20% implied probability chance), rising to 3/1 (25%) on Thursday.

It came after Leader of the Opposition Jeremy Corbyn refused to say he wanted an election, despite goading from Johnson throughout Wednesday and after the evening's vote.

The Labour Party chief said the offer of an election was "a bit like the offer of an apple to Snow White and the wicked queen" because what was really on offer was "not an apple or even an election but the poison of a no-deal (Brexit)".

However, the data from Oddschecker, which is updated every single day this year, gave Corbyn's formation a lead only twice in the past eight months.

"When observing the data day-by-day from the start of the year, the crossover between Labour and Conservatives is quite something," Oddschecker spokesperson Callum Wilson said in a statement.

"Only twice have Labour become favourites in the market, in January and in May. Otherwise, the chaos that seems to have enveloped the Tory government has not translated to the betting market," he added.

Tied in third place on Thursday when considering their predicted chances of winning the most seats in snap elections, were the Liberal Democrats and The Brexit Party.

Both were given odds of 20/1 by Oddschecker, equating to just over 4.7% chance.

READ MORE: Watch live: UK government faces showdown in parliament over Brexit

The ruling Conservatives have been bitterly divided over Brexit with their divisions resulting in the Withdrawal Agreement championed by former prime minister Theresa May being rejected three times by parliament.

It also led to her resignation and a subsequent leadership contest that saw Johnson installed in Downing Street.

Several Conservative lawmakers have also defected to the newly-established Independent Group for Change or to the anti-Brexit Liberal Democrats — the last of whom, Philip Lee did so on Tuesday, putting an end to the Conservative parliamentary majority.

To derail the opposition and rebel lawmakers' bid to stop the country from crashing out of the EU on October 31 — which he argues would weaken the UK's negotiating position with the bloc — Johnson said on Monday that he could call snap elections

READ MORE: ‘No to no-deal Brexit’: the Tory rebels defying Boris Johnson

Overall, the political deadlock over Brexit appears to have most benefitted the Lib Dems — to which Lee defected.

On January 2, their chance of winning the most seats in a snap election amounted to 250/1 but the price came crashing down with their odds calculated at 20/1 on Tuesday. Their best day was on July 24 — when Johnson became prime minister — with odds of 11/1.

A YouGov poll released last Friday found that 33% of the British electorate would vote for the Conservative party if snap elections "were held tomorrow."

The pollster put Labour and the Liberal Democrats neck-and-neck at 22% and 21% respectively, while the Brexit party was predicted to win 12% of the vote.