Conservatives and Lib Dems in the House of Lords say they will continue to oppose identity card plans despite MPs rejecting their earlier objections.
The ID cards bill will return to the Lords, after MPs voted in favour.
Ministers say anyone getting a passport should have to get an ID card and be registered on a database. Opposition peers say people should have a choice.
Sources predict "protracted conflict" between the Lords and the Commons.
Peers will not seek to defy MPs over earlier demands for an estimate of the full costs before the scheme's launch.
They had wanted the government to be obliged to set out how much the scheme would cost before the Identity Cards Bill came into force.
Earlier this month, MPs backed plans to oblige everyone applying for passports from 2008 to also get an ID card. About 20 Labour backbenchers rebelled against the government.
This vote overturned earlier Lords objections to the plan.
If the Lords and the Commons continue to differ over the issue the bill could theoretically "ping-pong" between them, until one side gives way or a compromise is reached.