Gordon Brown has been called upon to confirm his position on ID cards, amid increasing Westminster speculation he will abandon the government's controversial scheme once prime minister.
With rumours mounting Mr Brown will move away from a national ID card scheme - increasingly criticised for its cost and implications for civil liberties - the shadow home secretary David Davis has called on the soon-to-be prime minister to make his position clear.
Launching his leadership bid, Mr Brown said he intended to strike a different note to Tony Blair on many key issues, including a greater safeguard on civil liberties.
At the time he said this would not mean scrapping the controversial ID card scheme, but it has increasingly been questioned whether Mr Brown is waiting until he is firmly in power to announce a change of policy.
David Davis reiterated Conservative calls for the government to abandon the ID card scheme, citing increasing concerns and escalating costs.
Independent estimates now place the total cost of the ID card scheme at £20 billion. Mr Davis said the savings obtained by dropping the scheme could be used to fund a dedicated border police force, extra prison places and more drug rehabilitation programmes.
In an open letter to Mr Brown, Mr Davis said: "As chancellor you already bear responsibility for the £58 million of taxpayers money wasted on this expensive white elephant."
He continued: "Experts in the field warn that, far from making us more secure, ID cards risk making us less safe. By clustering a mass of personal information in one place, ID cards will make us a prize target for hackers, fraudsters and terrorists.
"Microsoft's UK technology officer warns of a 'honey pot effect'. Suffolk's chief constable fears that ID cards will be the 'gold standard' for criminals to aim for."
However, the Liberal Democrats believe Mr Brown will retain ID cards once prime minister. Home affairs spokesman Nick Clegg said the raft of criticisms levied at the scheme sees the government change its justification every month.
"Finding new excuses to foist ID cards on the British people will hardly be an act of great statesmanship from Gordon Brown," he said.
"If Gordon Brown were honest about the scheme's failings he would pull the plug the moment he enters 10 Downing Street."
Jack Straw, Mr Brown's campaign officer and a likely contender to return to the Home Office, insisted ID cards would be reviewed under the new government.
Mr Straw has been a noted opponent to ID cards so far, but like Mr Brown has been reluctant to signal a government U-turn.