Jeremy Corbyn has vowed to fight a leadership challenge from former shadow business secretary Angela Eagle as peace talks aimed at resolving the crisis at the top of the Labour Party collapsed.
The Labour leader's spokesman said it was "disappointing" that his deputy Tom Watson had walked away from the union-brokered talks which were attempting to end the impasse between the embattled Mr Corbyn and his MPs.
The collapse of the talks prompted Ms Eagle to announce her intention to fight for the leadership, saying Mr Corbyn had failed "to lead an organised and effective" Parliamentary Labour Party and she would set out her "vision for the country" on Monday.
A spokesman for the party leader said: "Jeremy Corbyn has reached out to Labour MPs and made clear he wants to work with them to carry out his role as elected leader of the party.
"Jeremy regards the talks with trade union leaders as a vehicle to bring people together, and it is disappointing that some have walked away from them.
"Jeremy is committed to fulfilling all his responsibilities as democratically elected leader and will not betray the hundreds of thousands of people who elected him for a different direction for the Labour Party and a different kind of politics.
"He continues to be fully committed to working with the Parliamentary Labour Party and is ready to talk with as many people as necessary to assist that process, discussing policy initiatives and listening to ideas.
"He will remain leader of the Labour Party and will contest any leadership challenge if one is mounted."
Mr Watson pulled the plug on peace talks with the trade unions aimed at breaking the deadlock between Mr Corbyn and his MPs because "there is no realistic prospect of reaching a compromise" while the leader remained determined to stay in place.
Ms Eagle thanked Mr Watson, Parliamentary Labour Party chairman John Cryer, chief whip Rosie Winterton and the union movement for trying "to find a solution to the impasse Labour faces with a leader who has failed to fulfil his first and foremost duty, that is to lead an organised and effective Parliamentary Labour Party that can both hold the Government to account and demonstrate we are ready to form a government in the event of a general election".
She added: "On Monday morning I will announce my candidature for leader of the Labour Party. I will explain my vision for the country and the difference a strong Labour Party can make."
Mr Watson announced he had pulled out of the union talks, saying Mr Corbyn's intention to continue "come what may" meant "there is no realistic prospect of reaching a compromise" over his future.
The overwhelming vote of no confidence in Mr Corbyn by the party's MPs showed he had "lost the support of the PLP with little prospect of regaining it", Mr Watson said.
A crisis meeting had been expected to take place in Brighton on Sunday before the giant Unite union's conference in a final effort to break the deadlock over Mr Corbyn's future.
The deputy leader said there had been "significant progress" during the discussions with the unions but "since the talks began Jeremy has publicly declared his intention to continue as leader come what may".
"This means there is no realistic prospect of reaching a compromise that satisfies the majority of colleagues in the PLP."
Mr Corbyn, who was attending the Durham Miners' Gala, had earlier urged the party to "come together" in opposition to the Government and insisted he was "happy" in his role.
Asked whether he found his position "demeaning" in the face of the opposition from his own MPs, Mr Corbyn told Sky News: "Nothing's demeaning at all. I'm very happy.
"I do my job, I represent my constituency as a local MP, I represent my party as the leader of the party.
"Many people go through really serious struggles in their lives - struggles to make ends meet, struggles to get a roof over their head, struggles to medically survive.
"That's real pressure on them, my job is to try to point a different political course for everyone and that's what I'm doing and I'm very happy to be doing it."