Two of the candidates in the race for the Labour deputy leadership set out their stalls by promising to stand up to Gordon Brown.
Party chairwoman Hazel Blears and Cabinet minister Hilary Benn said they would be prepared to speak out against the Chancellor if they won the contest.
While Mr Brown looks almost certain to take over the party leadership from Tony Blair and become Prime Minister, the race to succeed John Prescott as his deputy is far more open.
Ms Blears, a loyal Blairite, has already declared she has the backing of 45 MPs - enough to secure her place on the ballot paper.
The Chancellor has a formidable reputation, and was described by former Whitehall mandarin Lord Turnbull as having "Stalinist ruthlessness".
Ms Blears described Mr Brown as a "tough man" but said that people want a leader who does not "vacillate or sit on the fence". But Ms Blears told ITV1's Sunday Edition: "I think that you can, in politics, have really good, robust discussions, you don't always agree 100%."
She also said she felt it was important to have a woman as deputy leader. "If you can get a man and a woman, then I think it's a great thing for politics," she said.
International Development Secretary Mr Benn said he was "very confident" of securing enough nominations to enter the race when the leadership contest formally begins next week. He told Sunday Edition he was capable of giving honest advice to Mr Brown by "being a straight talker and saying what I think".
Mr Benn said: "Part of the job (of the deputy leader) is sometimes to say things to the leader that he doesn't want to hear. And that I would do because it's part of the role. It's ensuring that the voice of government gets heard."
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Northern Ireland Secretary Peter Hain and Justice Minister Harriet Harman have both released lists of MPs nominating them for the job. Education Secretary Alan Johnson is expected to reach the required number of nominations comfortably, while centre-left MP Jon Cruddas has also said he is confident of appearing on the ballot.
