U.K. Prime Minister Boris Johnson, on the heels of a storming election win last week, is seeking to assure pro-Brexit voters by making it illegal for Britain’s departure from the European Union to be pushed past 2020 -- the latest sign that he does not intend to shift from his harder stance on the issue.

Johnson has promised to get his withdrawal agreement, negotiated with the E.U., through Parliament in the coming weeks after he won a significant parliamentary majority in last week’s election. It will result in Britain formally leaving the E.U. on January 31.

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However, that then triggers a transition period as negotiators get to work thrashing out a post-Brexit trade deal. That period lasts until the end of the year, but can at the moment be extended until 2022.

Johnson’s government will, on Friday, put before Parliament a tweaked version of the withdrawal bill that would rule out an extension in the transition period. It allows Johnson to put a period on the Brexit timetable, and assure voters that his Conservative Party’s central promise of “Get Brexit Done” is being delivered.

“Last week, the public voted for a government that would get Brexit done and move this country forward, and that’s exactly what we intend to do starting this week," a Downing Street source told The Daily Telegraph. “Our manifesto made clear that we will not extend the implementation period and the new Withdrawal Agreement Bill will legally prohibit Government agreeing to any extension.”

That move is already seeing opposition from some European leaders. According to the Times of London, E.U. negotiator Michel Barnier has warned that he believes it is “very unrealistic” to expect a free trade deal to be delivered by the end of the year.

The move suggests Johnson intends to barrel on with his tough stance on Brexit that took him into power earlier in the year after the resignation of his predecessor Theresa May -- who stepped down after repeatedly delaying Brexit as her version of the withdrawal agreement was shot down again and again in the House of Commons.

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Some commentators had observed that after his election win on Thursday, Johnson has a striking majority in Parliament and is, therefore, less reliant on a small band of hardline Eurosceptics. Therefore, the theory went, he may adopt a softer stance on Brexit and be more open to delays. The new move indicates that is not the case and that Johnson intends to double down on delivering on the result of the 2016 referendum.

Johnson has put a rhetorical emphasis on his party sticking to its promises, likely aware of its majority coming from a number of key areas in the North and Wales that have traditionally not voted for the Conservative Party, including those that have not voted Tory in more than a century.

“To all those who voted for us for the first time, all those whose pencils may have wavered over the ballot and who heard the voices of their parents and their grandparents whispering anxiously in their ears, I say thank you for the trust you have placed in us and in me,” he said outside 10 Downing Street on Friday.

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In another sign of that push to be seen delivering on election promises, The Sunday Times reported that the government will enshrine its spending commitments on the country’s National Health Service into law.

The commitments and plans for the parliamentary year will be laid out in the Queen’s speech on Thursday, where Queen Elizabeth II will announce the government's legislative priorities. It is followed by a debate and a symbolic vote in the House of Commons.