Tory backbenchers critical of Mr Osborne's performance at the Treasury are said to be considering writing a letter to the Prime Minister calling on him to sack the Chancellor.
Threats have been made that a no-confidence motion could be triggered next year if Mr Osborne's next budget does not help revive the flatlining economy.
One Conservative MP was quoted as saying: "I have seen no evidence of a plot, but there is an almost universal view that George Osborne is out of his depth. I have no doubt that the vast majority of MPs feel that way."
Another added: "People across the party are unhappy about George; you will not find a single MP who thinks he is doing a good job, either economically or politically. There is a lot of anger directed at him."
Yesterday, faced with apparent growing unease, the Chancellor said: "People understand across Britain that it is a very difficult economic situation and we are going to have to take difficult decisions ... the country has to pay its way in the world and I am absolutely focused on that."
No 10 made clear the Prime Minister had full confidence in Mr Osborne.
However, Chris Leslie for Labour said growth was disappearing and the economy was stagnating. He added: "It's no wonder there is a whispering campaign against the Chancellor and potentially a leadership challenge from the Conservative backbenches."
Last weekend, reports claimed Adam Afriyie, the Conservative MP for Windsor and the party's first black MP, planned to run as a so-called "stalking horse" candidate should the PM lose the confidence of his party. However, the backbencher insisted he would never stand against Mr Cameron.
Meantime, the Prime Minister's recent high-profile speech on Europe may have cheered Conservative supporters but it has done little to improve the party's chances of General Election success, according to polling by major Tory donor Lord Ashcroft.
The peer, who until 2010 was Conservative deputy chairman, said Mr Cameron's promise of an in/out referendum following renegotiation of the UK's EU membership after the 2015 election had "not unleashed a desire for an overall Conservative majority".
In fact, it appears to have bolstered pro-European sentiments, with the number saying they feel positive about British membership increasing from 18% to 22% and those thinking the UK would be better off out falling from 34% to 26%.
Lord Ashcroft's telephone poll of 1000 adults left Labour in the lead on 38% against the Conservatives' 33% and Liberal Democrats' 11%. The UK Independence Party was on 9%.
In a separate development, the PM's renegotiation hopes were boosted by the Polish ambassador to the UK, Witold Sobkow, who said Warsaw was willing to accommodate some British demands. Asked if Poland would be ready to consider changes to the UK's position, Mr Sobkow said: "Yes. We see a lot of room for manoeuvre. We all want a better-functioning EU."