The US Senate is poised to approve today its version of an $838-billion economic stimulus package that will have major ramifications for US science. Eventually.

Barack Obama has made pushing through the stimulus bill through Congress a top priority of his young administration. But lawmakers in both houses, and both parties, all have varying opinions on how to do that. The version approved by the House on January 28 contains massive injections of funds for science in many arenas (see earlier Nature news stories here and here). The Senate version contains comparatively less in some research areas, and much more in others.

Negotiators will now have to haggle out the differences in the two bills before agreeing on a compromise that they will pass to Obama to sign. Congress had hoped to do this before the upcoming President’s Day holiday this weekend, but it is unclear whether enough time is left to make that self-imposed deadline.

Some key differences in the Senate bill include:

$10 billion for the National Institutes of Health, compared with the $3.5 billion approved by the House. The extra money came tucked in an amendment sponsored by Arlen Specter, Republican of Pennsylvania. Specter was part of the bipartisan group of senators who hashed out most of the details of the Senate bill going to the floor today.

$1.2 billion for the National Science Foundation, as opposed to the $3 billion approved by the House.

$1.3 billion for NASA, as opposed to the $600 miillion approved by the House.

$1 billion for NOAA, as opposed to the $600 million approved by the House.

$330 million for the Department of Energy’s Office of Science, as opposed to the $2 billion approved by the House.

Remember, these would be one-time injections of funds into these agencies, who are still waiting to hear from lawmakers what their bottom-line funding numbers for the current fiscal year (which started last October) will be. Once Congress manages to pass those numbers retroactively, Obama is expected to lay out his funding plans for fiscal year 2010 later this spring.

The House and Senate appropriations bills can be followed at appropriations.house.gov and appropriations.senate.gov.