"Want to cap Congress — not carbon?" The question appeared, slogan-style, in an online notice urging Virginia voters to attend a Tea Party convention held last week in the state's capital, Richmond. Organizers say that more than 2,800 people attended the event, the largest meeting yet for the new political movement that is injecting an unusual degree of volatility into this year's US midterm-election season.

Credit: B. SMIALOWSKI/GETTY

Strong opposition to greenhouse-gas regulation is just one manifestation of a broader Tea Party theme: keeping government small. Now the Tea Party phenomenon (and the public ire it has tapped) has become the defining feature of a campaign that will determine who, on 2 November, occupies each seat in the House of Representatives and more than one-third of the seats in the Senate. With Democrats currently holding narrow majorities in both chambers, even a modest change at the polls could spell a wholesale transfer of power in Congress and a seismic shift in the US political landscape. The governorships of 37 states are also in play this year, including that of California, a research powerhouse. It is difficult to predict how all this will affect scientists and the government agencies that fund them, but with the US economy staggering under the burden of high unemployment and record-setting federal deficits, the new Congress, whatever its ideological bent, will preside over diminished resources and difficult choices.

Click here for more on the midterm elections.

"In the face of fiscal constraints to come, making decisions on where to cut and how that will affect our research and innovation effort is a very serious issue," says Anne Solomon, a senior adviser on science and technology at the Center for the Study of the Presidency and Congress, a think tank based in Washington DC.

An issue paper co-authored this year by Solomon calls for a "science and technology-enhanced Congress", in which legislators are broadly knowledgeable about science and have better access to technical expertise on the complex issues they face — from energy policy, to education, to economic and security matters. In fact, the opposite is likely to be true of the next Congress.

Several senior figures who are strong on science policy are retiring, or may be ousted in a Tea Party-boosted vote swing. Solomon worries that this could mean an influx of new players on Capitol Hill who are less committed to funding science research and education, and who lack "the general science and technology savvy" to make informed decisions.

The Tea Party's conservative message could also affect how science is treated in Congress. Last week's convention in Richmond featured appearances by politicians including former Pennsylvania senator Rick Santorum, who once tried to amend an education bill to promote the teaching of intelligent design, and Virginia attorney general Ken Cuccinelli, who recently renewed his efforts to investigate and discredit climate scientist Michael Mann, formerly at the University of Virginia in Charlottesville.

But the Tea Party's biggest influence stems from its small-government, cost-cutting agenda. This has been taken on board by the Republicans, who are currently leading in the polls and look set to win the House from their Democratic rivals. The Republicans' 45-page policy document, unveiled on 23 September, is telling in both its emphasis and its omissions. Although the words "tax", "taxes" and "taxpayer" appear 56 times in the document, the words "science", "research" and "education" do not figure once.

In the current Democrat-controlled Congress, science was given plenty of attention in spite of the economic crisis. The National Science Foundation and the National Institutes of Health received influxes of cash as part of President Barack Obama's economic stimulus package. Legislation such as the health-care reform bill and a bill to deal with oil spills (not yet passed by the Senate) also include provisions for funding research and development. Disputes between the parties on science spending have tended to be "differences of opinion on how much to invest in basic research, not on whether or not it was important", says Joanne Carney, director of the Center for Science, Technology and Congress at the American Association for the Advancement of Science in Washington DC.

In his inaugural address, Obama promised to "restore science to its rightful place", and he appointed prominent researchers and science-policy experts to key government roles. But as the stories on the following pages detail, science faces plenty of challenges for the post-midterm Congress to address.

And given the changing political climate, the new Congress looks likely to be even more polarized than the last. If Republicans are running the House, the Obama administration will be dealing with an adversary rather than an ally as it tries to push through changes in areas such as energy and education. As concerns about the deficit combine with an enthusiasm for scaling back government, science funding could see heavy reductions.