The MP for Berwickshire, Roxburgh and Selkirk voted against the deal in January, saying he believed it could “harm the integrity of the United Kingdom” adding: “I need to put my constituents and my country first ... I do not believe that this deal delivers for either.”
Now, despite there appearing to be no real difference to the deal on the table, he has decided to support the prime minister, saying that the only way to deliver Brexit and to provide certainty is to back the one deal that is on the table.
In a statement issued this morning, Mr Lamont claims that Borderers “are tired of the constant debate about Brexit and just want our country to move on.”
Mr Lamont said: “It was announced last night that the UK has secured changes to the deal.
“They include a legally-binding addition to the withdrawal agreement, which gives the UK the right to start legal proceedings against the EU if the UK was tied to the so called Northern Ireland backstop indefinitely.
“In addition, a new joint statement confirms that both the UK and the EU are committed to finding an alternative to the backstop by December 2020.”
He added: “Speaking to local businesses over the past few weeks, it is clear that a lack of certainty is the number one concern for many.
“Whether they support leaving the EU with a deal or leaving without a deal, they want to make plans for after Brexit.
“And people in the Borders are tired of the constant debate about Brexit and just want our country to move on.
“Clearly, I am disappointed that we have not been able to achieve more significant changes to the withdrawal agreement. However, I have a responsibility to my constituents and to businesses in the Borders.
“The reality is that we are now barely two weeks away from leaving the EU. The choice we all face is leaving with the only deal that is on the table, leaving without a deal or creating further uncertainty by delaying the whole process.
“The only way to deliver on Brexit and to provide certainty for businesses in the Borders is to back this deal. It means that the rights of EU nationals will be protected, there will be no significant change to the availability and price of food, and travel to the EU will be largely unaffected. The UK will also be able to negotiate trade deals with both the EU and the rest of the world.
“The EU and the UK are both committed to avoid triggering the Northern Ireland backstop. If the deal is approved by MPs today, work to secure a future trade agreement with the EU must start immediately.
“The SNP MPs will vote for further chaos and uncertainty on the instructions of their boss Nicola Sturgeon. They simply do not care about respecting democracy nor do they want stability for the United Kingdom. All they care about is having another divisive independence referendum.
“Businesses and residents in the Borders want certainty, and they want Scotland’s two Governments to move on from Brexit and start talking about things that really affect people’s lives.”
In the referendum on Brexit, 58.5% of Borderers voted to remain.