Reid hints he won't challenge Brown.
Mr Reid again refused to rule himself out but emphasised the "unity" at the top of the party ahead of the May 3 polls.
And he insisted there would be no "fracturing" of this when the Prime Minister stands down.
His comments came after the Chancellor conceded that a drubbing for Labour next week would reflect badly on him as well as Tony Blair - saying people "will be voting on all of us".
Mr Reid refused to say whether it was a "done deal" that Mr Brown would be the next premier, stressing that Labour MPs were focusing on "maximum unity" on the campaign trail.
"I predict that we will not only see that unity up to this election, but beyond this election, and rather than the expected fracturing of Labour beyond it, we will see a coming together of all of the Labour leadership beyond this election."
He said the leadership was in "total agreement" about how to address the key challenges of the next decade.