Speaking to Sky News on Sunday, Britain's Liberal Democrat Party leader Jo Swinson ruled out any possibility of supporting a government under Labour Party leader Jeremy Corbyn.
"No, Jeremy Corbyn is not fit to be prime minister", Swinson told the broadcaster.
The statement comes days after Corbyn announced earlier this week that he would "immediately legislate" for a second referendum in the event that Labour wins power in an election.
Corbyn's comment came amid reports of a serious split within the Labour Party's leadership over the issue of Brexit and a general election.
During a shadow cabinet meeting on Tuesday, the Labour leader was warned about the possible "trap" of a general election, as the party has not yet won back Remain voters from the Liberal Democrats.
At the same time, the option of calling a second referendum is caught between opposing forces - the Conservatives, many of whom advocate for a potential no-deal Brexit and the Liberal Democrats, who support revoking Article 50 and stopping Brexit without a referendum.
While UK Prime Minister Boris Johnson has vowed that Britain will leave the EU on 31 October with or without a deal, British lawmakers have adopted legislation forcing him to request a delay to the Article 50 deadline until January 2020 if an agreement has not been struck before the aforementioned date.