The U.S. Senate has approved a $2.1 billion increase to its proposed budget for the National Institutes of Health (NIH)—by far Harvard’s largest source of federal dollars.

Thursday’s vote came two days after University President Drew G. Faust testified before a Senate committee in favor of boosting the Institutes’ budget.

NIH’s funding has seen a real-dollars decline in the last three years, leading many scientists to criticize Congress and the White House for stifling biomedical research.

“The 13-percent loss in real dollars over the last five years is having a cascading impact that is slowing progress and threatening future research that could lead to cures and even ways to prevent disease,” Faust said in her Senate testimony on Tuesday morning.

The additional funding represents an 8.4 percent increase over this year’s budget—well above inflation for biomedical research, which was 3.9 percent last year, according to a federal government index.

Though the amendment passed the Senate 95-4, it faces a number of procedural hurdles before becoming law.

Similar efforts have failed in the past, and Kevin Casey, Harvard’s associate vice president for government, community, and public affairs, said that despite the “strong support” of the Senate, White House opposition could still stymie Harvard’s efforts, at least in the short term.

“Ultimately, we’re hoping the next president—whoever that might be—will adopt restoring funding for NIH to a reasonable predictable growth path as a priority,” Casey said. “We look for progress to be made, but we don’t look for it to be accomplished overnight.”

Faust shied from making predictions after her testimony, but indicated that she would continue to follow the issue closely and, if warranted, participate in a similar event next year.

The $2.1 billion would come from cuts in other federal programs, but the amendment does not specify the sources of the offset.

Another amendment, proposed by Sen. Edward M. Kennedy ’54-’56 to permit future Congressional action to provide more low-interest loans to college students, also passed in Thursday’s session.

—Staff writer Clifford M. Marks can be reached at cmarks@fas.harvard.edu