Senior Tories have warned against a "hard" and "harsh" Brexit after Theresa May indicated that would be the path Britain will take as it approaches a leave date of spring 2019.
Commons Education Committee chair Neil Carmichael and former minister Anna Soubry stressed the importance of the single market and warned a so-called "hard Brexit" with the UK outside the free trade zone would damage the economy.
Hours after the Prime Minister's declaration the UK will "make our own decisions" on immigration put her on collision course with the European Union (EU), Mr Carmichael told pro-Europe Tories the country must avoid a damaging Brexit "at all costs".
Speaking to a gathering of about 80 supporters and members of the Conservative Group for Europe, he said: "We would be unwise to challenge the democratic view but we would be reckless if we did not challenge some of the consequences of a hard or harsh Brexit.
"Because we have got to understand that if it is a hard Brexit, it is also a harsh Brexit.
"Whatever nuance that people might like to say, however people might like to describe Brexit, whether it's hard, soft or I would hopefully say, sensible, what we must avoid at all costs is a Brexit that damages our economy, damages our capacity as a nation to perform capably in the future and actually damages Europe."
Mr Carmichael appeared to reject Mrs May's stance on immigration, insisting people have been brought into the country to fill jobs which British people do not have the skills to do.
"We have got to recognise that our nation does need a proper connection with the single market and we've got to find a way of making sure that actually happens," he said.
"Because the interesting thing about that debate is you hear an awful lot about migration and migration issues.
"But, you know, one of the things that drove the migration argument was the fact that we need to have skills which we haven't got.
"One thing that we're going to have to do as a nation is pull our socks up over the issue of the skills that we have through this education system that we've got.
"That is one thing we've got to do but it underlines the need to be very sensible about the way in which we deal with the single market."
Earlier, Ms Soubry, a supporter of the Open Britain campaign, criticised Mrs May's decision to trigger Article 50 of the Lisbon Treaty before the end of March 2017 to begin the formal two-year process of leaving the EU.
"The Government must be careful about being gung-ho on Article 50," she said.
"With France and Germany holding elections next year, they should not be scared of taking the time to get this right.
"It is clear that the EU holds most of the cards in negotiations at the moment and any Brexit deal will need the consent of Parliament.
"As such, the Government should be pressing for a deal that keeps Britain open and engaged with Europe, including keeping us in the single market that supports millions of UK jobs."