Paul Nuttall has resigned as Ukip leader after his party's woeful showing at the General Election.
The Eurosceptic party had been hoping to make gains in Thursday's poll, with Mr Nuttall running a campaign pledging to "ensure there is no backsliding on Brexit".
But after Ukip failed to gain a single seat in Westminster - and with Mr Nuttall coming third in Boston and Skegness - he opted to leave his position, telling reporters: "A new era must begin with a new leader."
He said he had left the foundations for the new leader to build on and ensured that the party was "still on the pitch".
And he insisted Ukip was "more relevant than ever" and would play the role in the coming months of the "guard dogs of Brexit".
Mr Nuttall told a news conference: "It is clear that Ukip requires a new focus, new ideas and a new energy - and it is there amongst out ranks.
"I think, regardless of the score last night, I have laid the foundations for the future in this General Election campaign but it will be for someone else to build on those."
Asked about a future role for former leader Nigel Farage, Mr Nuttall said: "If Nigel Farage wants to come back, I would be more than happy to do a job swap. I'll take his slot on LBC and he can come back as leader of Ukip."
Earlier, Mr Farage said he did not blame Mr Nuttall for the party's poor showing.
Asked on LBC radio about the prospects of a comeback, he said: "Whether leading or playing a prominent role is perhaps a different question."
Mr Nuttall failed in his bid to win a Commons seat on Thursday, finishing a distant third in Brexit heartland Boston and Skegness behind the Tories.
It was the Ukip leader's sixth attempt to get into Parliament, having finished second behind Labour at the Stoke-on-Trent Central by-election earlier this year.
The party was hoping to make gains in the Lincolnshire seat, which yielded one of the highest votes for Leave in last year's EU referendum.
But Mr Nuttall saw Ukip's share of the vote slide 26.1% to 3,308 votes, while Labour increased its vote by 8.5% to 10,699 and the Tories by 19.8% to 27,271.
The decline in the Ukip vote was seen across the country, with the party's vote share down to around 2% nationally, splitting between Labour and the Conservatives.
Asked what next, Mr Nuttall replied: "What now for me? Holiday. Or if that bar is open, a pint..."
The party announced that former Ukip chairman Steve Crowther had been elected "overwhelmingly" by the national executive committee to lead the party on an interim basis while the election of a permanent leader took place.