LONDON — Pro-EU Conservative MP Ken Clarke believes that Theresa May must "tackle Brexit on a cross-party basis" for the national interest.

Ken Clarke, who is Father of the House as the longest serving MP in the Parliament, told the Today programme on Wednesday morning that "you cannot carry out this negotiation on the basis that every aspect of this is going to be negotiated with the DUP... and then you have to get the entire Conservative Party to agree with it.

"Both parties [Labour and the Conservatives] are hopelessly split on the issue."

In practice, this would mean the Tories finding a consensus deal with Jeremy Corbyn's Labour and other opposition parties like the Lib Dems and SNP over Brexit.

The Labour Party favours a 'softer' Brexit than the government proposed in February, but it remains unclear whether this would potentially include remaining in the Single Market.

Clarke said: "We would restore confidence in politics if we can show that this Parliament can function in presenting a view in the national interest which can win a majority."

His comments follow the General Election where no party won enough seats for a majority. Even with the support of the Democratic Unionist Party, May will have a wafer-thin majority in the House of Commons.

Clarke has been MP for Rushcliffe since 1970 and served in Margaret Thatcher, John Major, and David Cameron's cabinets. He said May is "facing a bigger test than any other prime minister in my time."

The Financial Times reported this morning that former Prime Minster David Cameron has also called on May to "listen to other parties" on Brexit, including Corbyn's Labour opposition.

Clarke backed Remain in last year's EU referendum, but said that "the parliamentary vote in the last parliament settled the doubt we are leaving... we are now destined to leave the EU."

Responding to reports that French President Macron told May yesterday that Brexit can still be reversed, the veteran MP said: "he is wrong."

Clarke also backed May remaining in Number 10 despite her failure to retain the Conservative Party's parliamentary majority at Thursday's general election.

"I can't see for the life of me anyone else who could conceivably take over as PM. She's alright," Clarke said.

Conservative Party talks with the DUP are expected to be completed today.