Chris Evans has announced he is leaving his role as a presenter on BBC Two's Top Gear after one series.
He tweeted: "Stepping down from Top Gear. Gave it my best shot but sometimes that's not enough.
"I feel like my standing aside is the single best thing I can now do to help the cause."
His resignation comes after falling ratings for the show - which hit a series low on Sunday night, with an average of 1.9 million viewers.
BBC News understands the remaining five presenters - Matt LeBlanc, Rory Reid, Chris Harris, Sabine Schmitz and Eddie Jordan - will return for the next series, which is due to begin filming in September.
It is also believed Evans's decision to leave was his alone, and that he told the BBC last week he was stepping down, saying he was not a good fit for the programme.
Analysis - Lizo Mzimba, entertainment correspondent
What next for Top Gear?
Top Gear is one of the BBC's most important shows. It's brought millions of viewers to the BBC, many of whom aren't big users of other BBC services. And internationally it's worth tens of millions of pounds to BBC Worldwide.
While there's been a significant fall in viewing figures, interest in and awareness of the programme remains high - the latest series with Chris Evans and Matt LeBlanc was sold to 130 territories outside the UK.
But crucially it doesn't appear to have been able to recreate the relationship between the presenters that it enjoyed with Jeremy Clarkson, Richard Hammond and James May. The banter between the three was at least as important as the cars, and much of the audience feel that important element which made it more than a motoring show has been lost.
Few doubt the current presenting team's knowledge and passion for cars, and it's thought that the remaining members will be returning. When they do it's likely many viewers will perhaps be looking for the relationship between them to be built on, in order to bring the show closer to what it has been in the past.
Evans joined Top Gear last June, after the departure of Jeremy Clarkson, Richard Hammond and James May.
Clarkson was dropped from the show after he punched a producer following a row about the provision of food late at night while filming on location.
Perry McCarthy, the original Top Gear Stig, told the BBC: "It's sad for Chris but personally I was expecting such an announcement, I wasn't expecting it this quickly but I did think that Chris would step down from it.
"Chris is an enormously popular radio presenter and TV show host but he hasn't quite gelled with this show, he's not really gelling with the viewers.
"It must be a little bit painful for him to receive this reaction from everybody and I don't think he'd want to continue, I probably wouldn't want to continue if I was getting constant criticism either," added McCarthy.
Vassos Alexander, sports presenter on Evans's Radio 2 show, said Evans had indicated on Monday morning that he was leaving.
"I know that he was massively honoured and privileged to work on Top Gear and that statement is not just a statement," Alexander said.
"He [Evans] texted me what he's written for his newspaper column and he's described himself as a square peg in a round hole and I think that pretty much sums it up."
Alexander added: "He really put his heart and soul in to it - for what it's worth I thought it was a terrific programme - the reception which wasn't great at the start has become better and better.
"I've been to a couple of the recordings - it seemed like a really happy team, a really professional team. I'm kind of surprised and kind of not."
In a statement released via the BBC, Evans said: "I have never worked with a more committed and driven team than the team I have worked with over the last 12 months.
"I remain a huge fan of the show, always have been, always will be."
Evans, who has fronted the show throughout its current six-episode run, confirmed on Twitter he would continue with his other BBC commitments, including presenting the BBC Radio 2 breakfast show.
Mark Linsey, director of BBC Studios, said: "Chris is stepping down from his duties on Top Gear. He says he gave it his best shot doing everything he could to make the show a success.
"He firmly believes that the right people remain, on both the production team and presenting team, to take the show forward and make it the hit we want it to be."
Top Gear added on its website: "Everyone at TopGear.com wishes Chris all the best for the future."