At least two British Conservative MPs - and possibly as many as six - have called for a vote of no confidence in David Cameron's leadership of the party, according to reports in a sunday newspaper.
The report, in the Sunday Telegraph, did not name any of the MPs supposedly involved, and aides indicated that it was not being taken seriously by the party leadership.
But its appearance in a paper read by many Conservative activists and sympathisers will add to the pressure on Mr Cameron following a string of poor polls and the party's third place in this week's by-elections in Sedgefield and Ealing Southall.
According to the paper, at least two MPs and possibly as many as six have written to the chairman of the backbench 1922 Committee, Sir Michael Spicer, requesting a vote of no confidence.
A vote would automatically be triggered if letters were received from 15% of the parliamentary party - currently 29 MPs - as happened when Iain Duncan Smith was ousted as leader in 2003.
While there is no prospect of that threshold being reached, the dispatch of any letters would indicate a level of concern on the Tory backbenches about the direction Mr Cameron is taking the party in.
Discontent with his approach surfaced in the recent row over grammar schools. And there were criticisms of Mr Cameron's handling of the Ealing Southall by-election from some Tories.
Mr Cameron's espousal of causes like climate change and social responsibility ahead of traditional Tory concerns like tax cuts and immigration have led to grumbling among right-wingers.
The Sunday Telegraph quoted an unnamed MP as saying he had written a letter: "I felt I had to register my deep-seated dissatisfaction. I am not the only one and I know there are a number of others who are thinking of writing."
The paper said that Sir Michael Spicer refused to confirm or deny whether he had received any letters, and he made no immediate response to a request for a comment. A party spokesman declined to comment on the report.