Democratic lawmakers filed a federal lawsuit Monday in an effort to force the Bush administration to turn over estimates of the cost of last year's Medicare (search) legislation.

The suit was filed in U.S. District Court in Los Angeles, hometown of Rep. Henry Waxman (search), one of 19 Democrats challenging the administration's refusal to provide the documents.

They are relying on a 1928 law that they assert enables seven lawmakers who serve on the same committee to obtain information from the administration.

Bill Pierce, a spokesman for the Department of Health and Human Services (search), said the lawsuit was politically motivated.

HHS said last month that Democrats have no right to review its estimates that the Medicare overhaul would cost substantially more than the amount disclosed last year by President Bush and HHS Secretary Tommy Thompson.

Bush and Thompson repeatedly said the legislation would cost no more than $400 billion over 10 years, even as Medicare's top analyst forecast it would cost at least $100 billion more.