Science and politics are uneasy bedfellows. The first is built on evidence and objectivity; the second thrives on opinion and persuasion. Nowhere is that relationship more fraught than in the United States, where the need to win votes can trump scientific evidence on issues such as climate change and public health — and where scientists may have little sympathy for political give and take. This week, Nature scrutinizes the intersection of politics and science in the run-up to the US election on Tuesday 6 November. With the presidency, all 435 spots in the House of Representatives and 33 of the 100 seats in the Senate at stake, the outcome could change the course of US science for the next four years.

nature.com/election2012

When Barack Obama swept into office, he pledged to make science a guiding tenet of his leadership. A News Feature on page 488 examines how that pledge has fared in the face of hard political realities and crises such as the Deepwater Horizon oil spill.

A pair of Comment pieces examines the relationship between scientists and Congress. On page 494, Lawrence Goldstein, a stem-cell biologist at the University of California, San Diego, urges researchers to hound their congressional representatives to make the case for funding science. And on page 493, Rush Holt, a physicist and Democratic congressman from New Jersey, says that Congress would function better if more of his colleagues thought like scientists, or sought their advice. Such interactions would leave both politicians and scientists better informed — and the relationship between their fields a little less fraught.