The future of George Osborne as shadow chancellor was under renewed scrutiny last night amid attacks by party members who claimed he risked undermining sterling.

Activists contributing to party websites have labelled his interventions on Gordon Brown’s economic policy as ill-judged. Some on the ConservativeHome website voiced fears that he could cost the party the next election.

“It is extremely hard to find anyone in the City who now takes him seriously,” said Mark Hudson, one contributor.

Senior Tories at Westminster are openly debating whether Osborne could be replaced by a more experienced figure such as Ken Clarke, the former chancellor, or William Hague, the former party leader.

The backlash against Osborne was sparked by comments he made that the large-scale government borrowing was in danger of triggering a “proper sterling collapse”. This was seized on by Labour, who accused the shadow chancellor of talking the economy down “in a last throw of the dice to save his career”.

Osborne’s comments, in an interview with The Times, were being interpreted at Westminster as an attempt to regain the initiative after the controversy following his discussion of a party donation from Oleg Deripaska, the Russian tycoon.

His criticisms of the effect of Brown’s policies on sterling were backed by supporters who say he is doing a good job in difficult circumstances.

“There are elements of the party who are in danger of talking themselves into difficulties. We have got to stop worrying about personalities and focus on the crisis in the economy,” one shadow cabinet minister warned.

Some Tory MPs have accused David Davis, the former shadow home secretary, of stirring up the row for his own ends. But Davis has privately made it clear that he has no interest in Osborne’s job.

Last night Ken Clarke, the Tory grandee, came to the shadow chancellor’s defence, saying he has made “a perfectly sensible comment”. He added: “Gordon Brown reminds me of Harold Wilson blaming the weakness of sterling on people ‘selling the pound short’ when it had already been weakened by his government.”

It was also reported this weekend that Oliver Letwin, Osborne’s predecessor as shadow chancellor, has been drafted in by the Tory leader to draw up a package of spending cuts.

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