The debate on Social Security reform shifts on Thursday to the House of Representatives, where Bill Thomas, the chairman of the ways and means committee, intends to widen debate on the pension programme to embrace other retirement and tax issues.

Mr Thomas hopes his favoured approach will help end the stand-off over personal accounts, the centrepiece of President George W. Bush's proposed reform, which Democrats and some moderate Republicans have opposed. But the additional elements may also open new areas for disagreement and make it more difficult for action on the issue this year.