Nick Clegg, the favourite to succeed Menzies Campbell for the Liberal Democrat leadership, has vowed to lead a grassroots movement against ID cards.
Mr Clegg said last night he would refuse to register his details on the ID database and would encourage others to do the same.
Likening his stance to Poll tax resistant, he said: "If the government seeks to make ID cards compulsory on every British citizen I will lead a people's campaign to thwart the programme. I, and I expect thousands of people like me, will refuse to be forced to register.
"This is an issue that is so contrary to the spirit of British liberty and privacy that I would not be able to stand by. I am willing to do everything in my power to stop this intrusive, expensive and unnecessary imposition on the liberty of the British people."
Under existing powers, personal details supplied for a passport or driving licence application can be based to the ID card database after 2010.
MPs will need to pass further legislation to require all individuals to register for the compulsory ID cards and it is this Mr Clegg vowed to resist.
The government is insistent compulsory ID cards will come into force. The first wave begins next year with compulsory registration for foreign nationals.
Nominations for the Liberal Democrat leadership close today, with Mr Clegg - who is currently home affairs spokesman - the bookies favourite.
Environment spokesman Chris Huhne looks set to be his only opponent and the two MPs admit little differentiates them on policy.
Mr Huhne has, however, vowed to scrap Trident as well as placing constitutional reform as a precondition for any coalition.
Although Mr Clegg is more popular among Liberal Democrat MPs, it is the party's 55,000 strong membership that will decide the next leader, to be announced in mid December.