Sadiq Khan has said Labour must not just focus on its "core vote" if it is to win the next general election, in what has been seen as a clear criticism of Jeremy Corbyn.
The new mayor of London was speaking to the BBC's Andrew Marr programme on Sunday morning.
Khan's comments came after he wrote an article in The Observer in which he said the party needed to appeal to more than just "natural Labour voters alone".
Offered several chances to deny his newspaper column was an attack on Corbyn, Khan avoided doing so.
"We in Labour, our mission is to improve people’s lives and change people’s live for the better. We only do that by winning elections,” he told Marr.
"We only do that be speaking to those people who previously haven’t voted Labour, by speaking to Tory voters, by speaking to those outside of our tent. We’ve got to stop talking about ourselves."
"I want a big tent. Whether you are a Conservative trying to be the major of London or a Labour Party trying to form the next government, we’ve got to speak to everyone. There is no point us just speaking to Labour voters, our core vote."
Khan also refused to deny his argument that Labour should not campaign based on "picking sides" was a direct attack on Corbyn's local election slogan that told voters elections were about "taking sides".
Corbyn appeared to snub Khan after he failed to appear at the new London's mayor's signing-in ceremony yesterday.
Khan told Marr he expected to see the Labour leader tomorrow. Corbyn, who decided to travel to Bristol to congratulate the new Labour mayor of that city rather than see Khan, said he and the new London mayor were "getting on fine".
Khan said he was "happy to talk" to Labour activists and MPs if they wanted to learn from him "how to campaign and win elections or run a successful administration".
Several centrist Labour MPs have expressed agreement with Khan's analysis of how Labour should win elections.
Alastair Campbell, Tony Blair's former spin doctor, told ITV's new Peson on Sunday programme, that he agreed with "virtually every word" Khan had written.
