A Cabinet minister left the door open to extending Britain's transition out of the European Union as backbenchers warned Theresa May the deadline must remain intact.
Under the current timetable the implementation period is set to end
in December 2020.
But Business Secretary Greg Clark refused to rule out an extension to the arrangements.
He told Ridge on Sunday on Sky News: "At all times we need to be guided by the evidence on this, speaking to the people that run this very successful port (Dover) and the same with Eurotunnel, in order to make sure that we can continue the success, and that we don't have frictions, there are things that would need to (be) put in place, computer systems for example, posts at the border, even if they checked, automatically, number plates.
"What we need assess is how long it would reasonably take to put in practice and then it seems to me that any reasonable person would have to be guided by the facts and the evidence."
Mrs May will bring together her Cabinet on Friday at Chequers to thrash out details of a white paper setting out the UK's plans for areas such as trade.
Brexiteers oppose the PM's favoured option of a customs partnership with the EU, which would see the UK collect tariffs set by the EU customs union on goods entering the country on behalf of the bloc.
Their "max fac" alternative would, rather than scrapping customs checks, uses technology to minimise the need for them.
Both options have been dismissed by the EU.
Asked if the customs partnership option was still on the table, Mr Clark said: "Yes."
Mrs May faced a warning from backbenchers not to extend the transition period beyond December 2020.
Andrea Jenkyns, who quit a junior government role to campaign on Brexit, delivered a letter to the PM on Friday signed by more than 30 Tories calling for her to show "courage and leadership".
The group said: "Our departure must be absolute. We must not remain entangled with the EU's institutions if this restricts our ability to exercise our sovereignty as an independent nation.
"Anything less will be a weakening of our democracy. Britain must stand firm."
Senior Tory Sir Graham Brady, however, warned that disunity in the Cabinet was making Mrs May's negotiations with Brussels more difficult and would alienate voters.
In an article for the Observer, Sir Graham, chairman of the 1922 committee of backbench Conservatives,said: "Electorates these days are volatile, but one thing is certain: they do not vote for divided parties."
James Brokenshire said there was "no doubt that there is strong views on either side" over Brexit in Cabinet but insisted he was "confident" Mrs May's top team could reach an agreement on Friday.
The Communities Secretary said the Government was planning for "all eventualities".
NHS England chief executive Simon Stevens revealed there was "significant planning" going on to ensure the health service was ready for a no-deal Brexit.
He told BBC One's Andrew Marr Show the NHS had been working with the Government to ensure "medicine supply" continues in any Brexit scenario.
Labour leader Jeremy Corbyn said he believed the transition period after Brexit would be extended.
He told Ridge: "At the moment it's not set in stone, it's talked around for two years.
"I've got a feeling it might go beyond that."
Asked if he would be happy with that, he replied: "Yes."
Mr Corbyn sidestepped questions about whether he would rule out a second referendum.
"We have not proposed it, we have not supported it and we are not proposing it now," he said.