Prime Minister Theresa May and opposition Labour Party leader Jeremy Corbyn during the State Opening of Parliament on June 21, 2017 in London, United Kingdom.

Hopes that the U.K.'s two largest political parties can hash out a Brexit agreement have ended.

Six weeks of talks between the most senior lawmakers from the ruling Conservative Party and main opposition Labour party have ended with no deal. Labour leader Jeremy Corbyn wrote in a letter to Prime Minister Theresa May on Friday that talks had "gone as far as they can go" and his party will now oppose her Brexit proposal.

Corbyn added that the lack of support behind May and the likelihood that she will soon be replaced as prime minister had undermined talks.

"The increasing weakness and instability of your government means there cannot be confidence in securing whatever might be agreed between us," he said.

As skepticism grew over a cross-party deal, the pound has embarked on nine straight sessions of losses versus the euro, marking the longest unbroken run of losses this century. Versus the dollar it dipped to $1.2760 on Friday, marking a four-month low. This after almost reaching $1.34 as recently as March.

It is now expected that the U.K. government will put various options, known as indicative votes, to Parliament instead. The last time lawmakers in the lower house of Parliament — the House of Commons — held such a series of votes on Brexit there was no majority preference for any outcome.