Owen Smith: Only one MP should challenge Corbyn
One of the two MPs hoping to replace Jeremy Corbyn as Labour leader says only one challenger should appear on the final ballot.
Owen Smith said there was a "widespread view" among MPs that there should only be one challenger, but that he was not sure how they should be chosen.
He suggested the party's deputy leader, MPs or executive committee could choose between him and Angela Eagle.
Mr Smith postponed the formal launch of his campaign after the Nice attack.
A leadership contest is under way after most Labour MPs signed a vote of no confidence in Mr Corbyn, who rejected their calls to stand down and won a battle to be automatically included on the ballot to be put to members.
Former shadow business secretary Angela Eagle was the first to mount a challenge, with Mr Smith - the former welfare spokesman - now also putting himself forward.
Speaking on the Daily Politics, Mr Smith said the party owed Ms Eagle a "debt of gratitude" for mounting the challenge, and that he had delayed coming forward himself because he had been visiting his brother in hospital.
His candidacy has sparked fears among Mr Corbyn's critics that he could split the vote from members opposed to the leader.
Mr Smith said: "I think there's a widespread view in the parliamentary Labour Party, and indeed amongst many of the members, that probably there should only be one challenger."
Asked how that challenger should be determined, he said: "I'm not sure yet. I think it's not really for me to determine how we get there as one of the challengers, but I am prepared to submit to whatever mechanism - whether it's the deputy leader of the party, or the parliamentary leadership of the party, or the NEC (National Executive Committee) come up with, or the PLP itself.
"I think we need to find a mechanism to get to there and I will absolutely stand by whatever that decision is."
Mr Smith also repeated his call for a second EU referendum, claiming voters had been "sold a pup" by the Leave campaign.
He said the poll should be held once the terms of the UK's Brexit negotiations are clear.
"The analogy I would use is that you would not go out and buy a car without having a look under the engine and checking it actually works," he said.
"That is what we have been asked to do with Brexit and now we have got an opportunity to test drive the car, if you like, over the next 18-month period and check whether we actually want to buy it."
The former shadow work and pensions secretary had been due to make a speech in Pontypridd, formally launching his campaign, but he said he would not go ahead as planned following the "heartbreaking" news from Nice overnight.
He tweeted in French: "Solidarity and fraternity with the French people."
In his planned speech, Mr Smith - who has been Pontypridd MP since 2010 - had been due to say he was the only one of a "new generation of Labour MPs" who could "secure Labour's future".
Mr Smith has been given a boost after one of Mr Corbyn's strongest supporters in Parliament transferred her support to him.
Jo Stevens, who has been MP for Cardiff Central since May 2015, said it had become "painfully obvious that we have been unable to fulfil the very basic day-to-day operation as the official opposition in Parliament" in recent weeks.
"We cannot present ourselves as a government-in-waiting without leadership and a leadership team that commands the respect and support of not only members... but Labour voters and potential Labour voters," she wrote in an e-mail to party members.
Despite facing a revolt from his MPs, Mr Corbyn retains the strong support of many party members and has said he will fight the challenges in a contest which is expected to be decided in September.
Mr Corbyn, who was accused by some MPs of not campaigning strongly enough for a Remain win in last month's EU referendum, has suffered dozens of resignations from his front bench.
Labour's ruling NEC said on Tuesday that Mr Corbyn would automatically go on to the ballot paper as the sitting leader. His challengers need the backing of 51 MPs or MEPs - 20% of the Parliamentary party - to stand.
Speaking outside the meeting, Mr Corbyn, who was elected as leader overwhelmingly in a vote of Labour members and registered supporters last year, said he would campaign on "all the things that matter".
Ms Eagle - who has already secured 51 nominations from MPs - has been calling for Mr Corbyn to resign for days.
She said she had eventually decided to launch a formal challenge because he was unwilling to stand down and she could provide the real leadership he could not.