Britain appeared to move a step closer Sunday to holding an early election in December, after two opposition parties backed the idea -- but only if EU leaders delay Brexit until

January. The Scottish National Party (SNP) and the Liberal Democrats broke ranks with the main opposition Labour party to offer Prime Minister Boris Johnson the snap poll he wants, only on their terms.

But his government dismissed it as a "gimmick", while the plan depends on how long European Union leaders will delay Brexit -- and they are watching to see what happens in London.

Britain is due to end its 46 years of EU membership on Thursday, but Johnson was forced by law to request a three-month delay after MPs last weekend refused to approve his exit deal, the latest twist in the tumultuous divorce process.

Exasperated EU leaders have agreed to a postponement but disagree over the length, with a decision due on Monday or Tuesday.

At the same time, Johnson will ask British lawmakers to back an early election. He wants a December 12 vote, hoping MPs will approve his divorce deal first.

But his minority Conservative government needs the support of opposition MPs, and they have previously twice refused.

The Labour party dislikes his Brexit deal and says it will not back an election until the risk of Britain leaving the EU with no deal at all is removed.

But in a new twist, the SNP and the Lib Dems -- which both strongly oppose Brexit and between them have 54 MPs in the 650-seat House of Commons -- have offered another way.

They propose that MPs give up on Johnson's Brexit deal and move to a December 9 vote -- as long as EU leaders agree to delay Brexit until January 31.

- 'See what the EU says' -

Members of Johnson's government dismissed the SNP-Lib Dem idea as a "gimmick" and a "stunt".

"If the SNP and Lib Dems want an election then they have a chance to vote for one as quickly as tomorrow when the government's motion is voted on," Culture Minister Nicky Morgan told Sky News.

Senior Labour MP Diane Abbott said her party would wait to hear from Brussels.

"We are waiting to see what the EU says. Make no mistake... the Labour party is up for an election," she told BBC television.

Guy Verhofstadt, the Brexit coordinator for the European Parliament, tweeted that the SNP-Lib Dem proposal was "sensible".

And France, which has so far objected to a three-month Brexit delay, said Sunday that an election would be a reason for a postponement.

"If they want to hold elections, we must give them the time to do that," European Affairs minister Amelie de Montchalin told French media.

- Holding Britain 'hostage' -

Johnson has proposed an election under the Fixed-term Parliaments Act, which requires the support of two-thirds of MPs -- 434 out of 650.

The SNP and Lib Dems propose instead passing a bill with the single purpose of holding a December 9 vote, which could pass with a simple majority.

"The SNP is prepared to back a bill that seeks to bring forward an early general election on Monday December 9 once an extension to the Brexit deadline to January 31, 2020 has been secured," SNP Westminster leader Ian Blackford said.

However, to even be debated the legislation requires government support or an emergency motion backed by a majority of MPs to make time in the parliamentary timetable.

Johnson, a leading Brexit figure in the 2016 EU referendum, is currently ahead in opinion polls.

But experts say the referendum upset traditional political allegiances, and voter volatility makes an election result hard to predict.

Downing Street is wary of a backlash among voters angry that Johnson missed his repeated promises to leave the EU on October 31.

But it could mitigate the damage by persuading MPs to ratify the divorce deal before an election -- or at least showing that they tried.

"Parliament cannot hold the country hostage any longer," Johnson said in a statement late Saturday.afp