The decision by Angela Eagle to pull out of the leadership contest demonstrates that she has the best interests of the Labour Party at heart.
The announcement came as Owen Smith won the backing of more MPs in the process of selecting a single candidate to take on Mr Corbyn.
Speaking to journalists at Westminster she said: “When I looked at the results I didn’t think it was in the interests of the party that this carried on.”
Ms Eagle added: “We have a Labour Party at the moment that is not working, we’ve got a leader that doesn’t have the confidence of his Members of Parliament and isn’t reaching out to the country.
“We need to have a strong and united Labour Party so we can be a good opposition, take the fight to the Conservative Government and heal our country.
“So I am announcing tonight that I will be supporting Owen in that endeavour with all my enthusiasm and might.”
Her withdrawal has cleared the way for a head-to-head battle between current leader Jeremy Corbyn and Welsh MP Smith.
There had been pressure from the Parliamentary Labour Party for a single candidate to run against Mr Corbyn.