The Trump administration has ordered the National Institutes of Health to halt the issuance of all new research grants, research-and-development contracts and training awards, according to a 30 July directive from the White House Office of Management and Budget. The suspension, described by officials as a short-term “pause,” freezes billions of dollars in congressionally approved funding for universities, academic medical centers and other research institutions with just two months left in the fiscal year. The blanket freeze follows internal NIH plans to pare back awards even before the OMB directive. The National Cancer Institute now expects to fund only about 4% of R01 grant applications—roughly one in 25—down from 9% earlier in the year, and several other institutes have been told to cut their success rates by at least half. Members of Congress have begun preparing challenges to the move, which critics say oversteps executive authority to withhold money that has already been appropriated. The funding clampdown extends beyond the NIH. Federal agencies have frozen roughly $200 million to $339 million in National Science Foundation, NIH and other grants to the University of California, Los Angeles, citing alleged antisemitism and discrimination on campus, and the administration has also blocked financing for a range of public-health programs run by the Centers for Disease Control and Prevention, according to agency and media reports.