The White House yesterday set out to defend its social security proposals, as President George W. Bush's job approval ratings this week fell to their lowest level yet barely 100 days into his second term.

At a news conference on Thursday, the president announced for the first time that he favoured means-testing for the scheme so as to reduce future benefits for middle- and upper-income workers while preserving them for the poor. His spokesman yesterday said a defeat of the president's proposal would guarantee that future benefit cuts fall hardest on poorer workers.