Britain’s Conservative Party is on course to win its biggest majority in parliament since 1987 at a Dec. 12 election, according to a new poll, which would give Prime Minister Boris Johnson a mandate to take the country out of the European Union.

The model developed by pollsters YouGov that accurately predicted the 2017 election result, showed the Conservatives are set to win 359 seats out of 650, which would be their best result since Margaret Thatcher’s victory in 1987.

Johnson has pledged to deliver Brexit by Jan. 31 if he wins after nearly four years of political crisis that has shocked allies of a country once considered one of the pillars of Western economic and political stability.

Since Britain voted to leave the EU in a June 2016 referendum, Johnson and his predecessor Theresa May have both tried and failed to get deals to leave the 28-member bloc through parliament because they lacked a majority.

“Our first MRP model projection for the 2019 election suggests that this time round the Conservatives are set for a majority,” said Anthony Wells, director of political and social research at YouGov, referring to its Multilevel Regression and Post-stratification (MRP) model.

“The swing to the Conservative party is bigger in areas that voted to Leave in 2016, with the bulk of the projected Tory gains coming in the North and the urban West Midlands, as well as former mining seats in the East Midlands,” said Wells.

The British pound, which rose when rumors of the poll results circulated, shot up when it was published, rising half a cent in minutes to hit a day’s high of $1.2948.

The main opposition Labour Party is on track to secure 211 seats, down from 262, according to the YouGov model. The Scottish National Party (SNP) was on 43, the Liberal Democrats on 13 and the Brexit Party was not expected to win any seats.

Reuters