The Guardian's editor has said the newspaper might endorse the Lib Dems instead of Labour at the next election.
The Guardian has backed Labour at recent general elections
At a talk in London on Tuesday, Alan Rusbridger said the switch from Labour would be "very dramatic" but there was "every chance" it could happen.
But he stressed no final decision on the move had been taken and any support would be decided "collegiately".
The paper has in recent years been a firm Labour supporter but backed the Lib Dems in the Hartlepool by-election.
At the talk, part of the Orange word season, Mr Rusbridger said: "The Guardian is a small 'l' liberal paper and has, at many times
in its history, supported the big 'L' Liberals.
"I think you only have to read the paper to see that we have a lot of worries
about the conduct of the New Labour government."
The newspaper has been a strident critic of the Iraq war and came out against Labour in the Hartlepool poll, while insisting its advice was a one-off and not a pointer to its general election stance.
The Daily Express has already switched its support from Labour to the Conservatives because of its opposition to the European constitution.
But the Guardian's Labour links stretch back much further and its loss of support would be seen as a blow to Tony Blair.