US investigators funded by the National Institutes of Health (NIH) may soon be compelled to publish only in journals that make their research papers freely available within one year of publication.

Congress is this week expected to take final votes on a bill incorporating this directive. The measure is contained in a spending bill that boosts the biomedical agency's effective budget by 3.1%, to $29.8 billion in 2008.

President George W. Bush has vowed to veto the bill, which will fund the Department of Health and Human Services and other agencies, because it includes what he calls ?irresponsible and excessive? levels of spending.

But congressional Democrats have attached to the measure an unrelated but politically popular bill funding the Department of Veterans Affairs. They hope that this will generate the two-thirds support needed in both houses of Congress to override a presidential veto.

The open-access requirement in the bill would apply only during fiscal year 2008; it would need to be renewed in yearly spending bills in the future.