Kevin Rudd has scoffed at reports he is within striking distance of toppling Julia Gillard for the federal Labor leadership.

"Give us a break, give us a break," he told reporters in Canberra on Tuesday when asked whether his backers were counting the numbers.

Mr Rudd was responding to reports that support for the former prime minister could be as high as 45 votes out of 102 caucus members.

Ms Gillard's supporters say it is lower, Fairfax Media says.

Mr Rudd insisted his position was unchanged from 12 months ago, after he comprehensively lost a leadership ballot 31 votes to 71.

"I supported the prime minister ... that remains my position," he said.

"Everyone should take a long, cold shower."

Ms Gillard's reduced support, confirmed to Fairfax Media by multiple sources from both sides of the caucus, raises the possibility of a second leadership challenge by Mr Rudd, although his supporters say no move is imminent.

The estimate of 45 votes for Mr Rudd is regarded as "not unrealistic" by a key Gillard backer, who put it "closer to 40".