Vince Cable, the leader of the Liberal Democrats, will step down from the role in May “to make way for a new generation”, he told party members.
The former government minister, who has led the small, pro-European party since 2017, said he would stand aside after local elections across England on May 2.
“I wanted you…to know that, assuming parliament does not collapse into an early general election, I will ask the party to begin a leadership contest in May,” Cable told Liberal Democrat members in a letter.
“I set considerable store by having an orderly, business-like, succession unlike the power struggles in the other parties,” he added.
The 75-year-old vowed last September to resign as leader once Brexit had been “resolved or stopped”.
He wrote that, following crunch votes in parliament this week which called for a delay to Britain’s departure from the European Union, his aim had been partly achieved.
“It is now clear that Brexit will be postponed, and very possibly stopped,” Cable stated.
“I indicated last year that once the Brexit story had moved on, and we had fought this year’s crucial local elections in 9,000 seats across England, it would be time for me to make way for a new generation.”
He added it had been “my great privilege to lead the Liberal Democrats at this crucial time”.
The party spent five years in a governing coalition with the Conservatives from 2010 but suffered an electoral backlash in 2015 and 2017.
It currently has 11 seats in the 650-member House of Commons.
Cable, former chief economist for energy giant Shell, has vehemently opposed Britain’s decision to leave the EU, warning it will damage the economy.
He entered parliament as an MP for the leafy London suburb of Twickenham in 1997, lost the seat in 2015, but then regained it two years later.