The left-winger now has the support of more than half of those with a vote in the Labour leadership contest, a YouGov suvery has suggested.
"If Jeremy's got a momentum behind him, which he has, that's a good thing. It's a good thing for our party and it's a good thing for the debate, but I still think overall that Andy is the candidate that will unite the party and bring the party forward," said Dawn Butler MP for Brent Central on Premier's News Hour.
Ms Butler also said Corbyn's participation in the leadership race had engaged more young people in politics, and praised Corbyn for encouraging and what critics argue is an idealistic agenda: "As a young person you're supposed to be uncompromising and you're supposed want to see a different world and want to change the world, so it's great to see that, " added Butler.
The survey for The Times of 1,411 eligible voters in the contest to succeed Ed Miliband found Mr Corbyn had nearly doubled his lead in a week to 32%.
It gave him 53% - enough to win without a need to count second preferences - with Andy Burnham losing five points to 21%, Yvette Cooper slipping two to 18% and Liz Kendall down three on 8%.
Mr Corbyn said: "The campaign is going very well but I think we should be a little bit cautious because there is still time for people to register to join the party or register as supporters and no ballot papers have yet been sent out and we won't know the result until next month. So let's be a bit cautious."
The Corbyn campaign has continued to gather momentum despite warnings from a string of senior party figures that choosing the veteran left-winger would be catastrophic for Labour's electoral chances, with one grandee comparing him to former Tory leader Iain Duncan Smith.
Tony Blair's former spin doctor Alastair Campbell has urged Labour supporters to sign up to vote for "anyone but Corbyn" to help the party "stop itself driving over a cliff".
Lord Soley, a former chairman of the Parliamentary Labour Party, compared the prospect of a victory for Mr Corbyn to Mr Duncan Smith's disastrous leadership of the Conservatives.
Serial rebel Mr Corbyn had been accepted as a "maverick" within the party but discipline was needed in Parliament, Lord Soley said.
He added: "It might focus minds before this important vote if we recall how delighted we were when Iain Duncan Smith became leader of the Tory party. We wanted him to stay. We should not fall into the same careless way of thinking."
Bookmakers have slashed the odds on a Corbyn victory following the YouGov poll.
Listen to Dawn Butler MP for Brent Central speaking to Premier's Antony Bushfield on the News Hour:
