Chancellor of the exchequer Philip Hammond has said getting behind Theresa May's Brexit deal would free up billions of pounds in extra public spending or tax cuts.
Hammond also dismissed the importance being placed on the Irish backstop, which could force the UK into an EU customs union in order to avoid a hard Irish border, claiming they are "not real world problems", according to the Financial Times.
The chancellor will announce a half-yearly budget update on Wednesday, a day after Parliament vote on Theresa May's deal to leave the European Union.
In an interview with the FT, he said official fiscal forecasts would demonstrate the improvement in public finances since the last budget update and that he would now have more than the £15.4bn in fiscal headroom than previously expected.
The 63-year-old called upon the Eurosceptic members of the Conservative party to back May's deal regardless of whether concessions are agreed before Tuesday's vote, playing down concerns that the backstop could leave the UK tied to the EU indefinitely.
“There is nobody in the EU I’ve ever come across who thinks the UK could be held in perpetuity in an arrangement that was detrimental to its interests against its will,” said Mr Hammond. “Who is going to enforce such an arrangement on this? How is the world’s sixth-largest economy going to be held in a necklock?”
May has admitted that a delay to Britain's exit from the EU could be a possibility if her deal, which was heavily beaten in January, is rejected again.
On Friday she urged the EU to make "just one more push" to break the deadlock but EU chief negotiator Michel Barnier's proposal that London can take Britain out of the customs union but forcing Norther Ireland to remain in alignment with EU rules, was outright rejected.
May also said the UK "may never leave" the EU if MPs vote down her revised deal next week.