The US House of Representatives has passed a bill requiring the government to negotiate directly with drug companies to obtain the lowest prices.
The government would have to negotiate prices with drug companies
The new Democrat-controlled House passed the bill despite a threat from President George W Bush to veto it.
It is the latest legislative measure to put Congress on a collision course with President George W Bush.
On Thursday, the House passed a bill backing embryonic stem cell research, something Mr Bush vehemently opposes.
Supporters of the bill say it will lower the cost of prescription drugs for Medicare beneficiaries.
Critics say competition among private insurers has already driven down the cost of drugs.
The new bills are part of a string of measures the Democrats are pushing forward in their first 100 hours in control of the new session of Congress.