The congressional noose around research in the social sciences and the geosciences at the National Science Foundation (NSF) got pulled a little tighter today as an influential legislator unveiled a new and controversial budget metric as part of his blueprint for the agency.

“I want to make sure that they are spending about 70% of their money on the core sciences,” says Representative John Culberson (R–TX), chair of the appropriations subcommittee that funds NSF and several other federal science agencies. Culberson spoke to ScienceInsider after his panel marked up a 2016 spending bill that would give NSF only $50 million of the $379 million increase it has requested.

Culberson, who this year succeeded the retiring Representative Frank Wolf (R–VA) as chair of the commerce, justice, and science (CJS) subcommittee, has thrown his weight behind a campaign by some Republicans to earmark more of NSF’s budget for what they have labeled the “pure sciences.” Their definition covers only four of NSF’s six research directorates—biology, computing, engineering, and math and physical sciences. It leaves geoscience and the social and behavioral sciences out in the cold.

The House spending bill marked up today would allow NSF to spread the additional $50 million in research across only those four favored directorates. That’s a meager 0.7% over current levels, compared with the 4.3% increase that the Obama administration has requested. The other two directorates would be kept at 2015 levels, as would the agency’s education activities, which were slated for an 11% boost. The bill also erases the $30 million hike that NSF has requested to prepare for its planned headquarters move in 2017 from Ballston to Alexandria in northern Virginia.

Right now NSF allocates 65% of its $5.93 billion research account to the four directorates that Culberson prefers. His spending bill would bump that up to 66%.

Representative Lamar Smith (R–TX), chair of the science committee, has made a similar distinction in the America COMPETES Act, a bill to set NSF policies that is scheduled to be voted on next week by the full House of Representatives. Under Smith’s legislation, which as an authorization bill doesn’t actually appropriate money, the favored quartet would receive 71% of the $6.19 billion that Smith has recommended for NSF’s research allocation.

Many scientists believe those disciplinary distinctions are merely a ploy by Republicans to hide their real goal—curbing federally funded research on climate change and political science. They also see it as part of an effort by budget hawks to shrink overall government spending. But Culberson and Smith say they are big supporters of NSF and are simply trying to make sure that everything it funds serves “the national interest.” Some areas of research are just more valuable to the nation than others, they insist.

“I’m asking them to prioritize,” Culberson says. “I want to give them as much freedom as possible, but also to encourage them, through the committee report, to make the hard sciences a priority—the math and physics and pure science. The fundamental mission of NSF should be those core sciences.”

That approach is wrong-headed and unwise, many scientists say. Society’s complex problems require participation from all areas of science, they say, as evidenced by the increasingly interdisciplinary nature of research.

Culberson says that the new spending bill “protects” such cross-disciplinary initiatives, including NSF’s proposed $75 million Innovations at the Nexus of Food-Energy-Water Systems, in which the geosciences directorate plays a major role. But he declined to say how that would happen. In contrast, the bill fully funds a requested 35% increase, to $144 million, for the Understanding the Brain initiative, a component of the administration’s cross-agency BRAIN program. The social and behavior sciences play a significant role in that effort, which is a consuming interest of the panel’s top Democrat, Representative Chaka Fattah (D–PA).

Today’s markup is the first step in a long process for setting NSF’s 2016 budget. The full committee is slated to meet next Wednesday in what is expected to be a rubber-stamp endorsement of the overall $51 billion CJS bill. The Senate has yet to begin work, however. And the two bodies must reconcile differing versions before anything is sent to the president.

Culberson hinted that the end product could be more generous. “I’ve had to scratch and scramble for that $50 million,” Culberson said, blaming the spending limits imposed by a 2011 law intended to reduce the deficit that triggered deep, across-the-board spending cuts in 2013 and led to a 16-day government shutdown later that year. Making reference to the rumblings that the White House and congressional Republicans could strike a deal that would raise those caps, Culberson added, “If I get any additional money, NSF is my top priority. But that’s down the road.”