WALLASEY MP Angela Eagle tonight quit the Labour leadership challenge to Jeremy Corbyn.
It leaves MP Owen Smith as the only remaining contender to face the Labour leader.
Her decision comes after a secret ballot on Monday night, by Labour MPs, to decide on a single challenger.
Smith polled the highest number of votes, 88 nominations from Labour MPs and two from MEPs, clearing the 51 needed to become a candidate. The deadline for any other contenders closes at 5pm on Wednesday.
If I win, Angela Eagle will be right at my side. She is a star and she will be my right-hand woman
Eagle said she would work "lock-step" with Smith when asked if the two had done a deal.
"Owen Smith will make a great leader for Labour and a great PM," she tweeted shortly after the announcement. He has the values, vision and policies we need to take on the Tories."
The fulsome praise cut both ways with Smith vowing: "If I win, Angela Eagle will be right at my side. She is a star and she will be my right-hand woman.''
As things stand, it's a sizeable "if". According to reports in the Dailt Telegraph, in the first 24 hours of a two-day window, more than 55,000 people paid £25 to sign up as Labour supporters, which will allow them a vote in a single leadership race.
Political analysts are suggesting bouyant Corbyn support and, with the Labour Party website grinding to a halt at one point today, it is believed tens of thousands more are likely to sign up before Wednesday's deadline.
Furthermore, according to a YouGov poll commissioned by The Times, of 1,019 Labour members surveyed between Friday 15 July and Monday 18 July, 44 percent said they would definitely vote for Corbyn in the September leadership contest. Another 13 percent were "probablies".
A Corbyn v Smith stand-off, it found, would secure 56 percent of votes for the current leader against Smith's 34 percent.
.@OwenSmith_MP will make a great Leader for Labour and a great PM. He has the values, vision & policies we need to take on the Tories— Angela Eagle (@angelaeagle) July 19, 2016
Nevertheless, Eagle said: "We have a Labour Party at the moment that is not working, with a leader that does not have the confidence of his members of Parliament and is not reaching out to the country.
"We need to have a stronger and united Labour Party so that we can be in a good opposition to take the fight to the Conservative government and heal our country."
Civil war broke out in the party in the days following Brexit when 172 Labour MPs at Westminster supported a vote of no confidence in Corbyn, who was elected last year as leader of the party with the biggest mandate ever. MPs claimed to be disappointed with his performance in the EU referendum campaign, with Labour officially backing Remain.
Already most of his Shadow Cabinet had gone, walking out in an on-the-hour drip feed of headline-grabbing resignations. But despite intense pressure to stand down, Corbyn stood firm saying he would not "betray" the membership wo had voted for him.
To all Labour women tonight feeling down & wondering if we'll ever have a woman leader of our party. Know this: we are not yet done