At many research universities, the deep federal budget cuts known as the sequester continue to cloud the future of laboratories and the scientists who staff them.

This week university presidents meeting in the nation’s capital denounced the sequester, as they have since before it took effect in March, and urged Congress to roll it back so that federally sponsored research can resume at a normal pace.

“The sequester is having a devastating impact,” said Elson S. Floyd, president of Washington State University. He was joined by others Monday at a news conference to release the results of a survey sponsored by the Association of Public and Land-grant Universities, the Association of American Universities and the Science Coalition.

In October, the groups asked 171 leaders of research universities about the effects of the sequester, and got 74 responses.

Seven out of 10 who responded said they had encountered delays in research projects since the sequester took effect, and the same share said their schools were obtaining fewer new research grants.

The toll goes on: 30 percent reported reductions in undergraduate student research; 35 percent, reductions in new federal training grants; 23 percent, reductions in admission of graduate students; 35 percent, cancellation of research projects.

In March, The Washington Post reported that about $30 billion a year flows from the federal government to universities for research and development. The sequester is likely to shrink that funding by more than $1 billion. But the full effect of the sequester on federal research funding is still unknown, university advocates say.

Whether Congress will roll back the sequester is hard to say. There has been political stalemate for months on key budget issues.

Gene Block, chancellor of the University of California Los Angeles (and a former provost of the University of Virginia), estimated that UCLA has lost about $50 million this year in federal research revenue because of the sequester. For perspective, UCLA received about $674 million in federal research awards in 2012.

The leaders of Stony Brook University (President Samuel L. Stanley Jr.) and the University of Colorado Boulder (Chancellor Philip P. DiStefano) reported similar troubles.

Block said UCLA has dipped into its own funds to ease some of the financial troubles of its vast research operations. But he said: “There’s a limited amount we can do to keep labs running.”