Tessa Jowell questions chances of a Corbyn government
Labour's Baroness Jowell has questioned whether "Jeremy Corbyn's Labour Party" has what it takes to win an election and form a government.
She said elections in May would be a "big first test" for the party as they face the London mayoral, Scottish, Welsh and English local elections.
The party had "turned left", she said, away from a centre-left position which she said had been "most effective".
Her comments come as Labour's membership has reportedly soared.
Baroness Jowell, a former minister in both Tony Blair and Gordon Brown's governments, told BBC London's Vanessa Feltz radio show that Jeremy Corbyn "carried a tide" with an "extraordinary level" of "enthusiastic support" from hundreds of thousands of Labour Party members.
However, she questioned whether ordinary people, not part of the party, would vote for its policies, she said: "Is its offer, policy offer, one which people who are not members of the Labour Party want to vote for because they feel it will meet their needs?"
She said: "Will the Jeremy Corbyn Labour Party actually become a party of government?"
"You can have a party which is a movement which satisfies its members, enthuses its members and engages its members, but the role of a great political party like the Labour Party is to become a party of government," she said.
Asked whether she thought the Labour Party could become a party of government she replied "I don't know yet, we're four years away" from the general election.
She said elections in May would be "the moment at which the new Labour Party is tested".
During Labour's London mayoral candidate contest she ran against Sadiq Khan, who won.
She said she "gave it everything I could" and "couldn't have fought a better campaign" adding "I didn't win because the Labour Party turned left".
The Labour Party has released its membership numbers which show increases linked to the election of Jeremy Corbyn as Labour leader.