More than 50 Nobel laureates are urging Congress to spare the federal science establishment from the looming budget cuts known as the sequester, saying that research has endured years of budget reductions and that additional cuts could endanger “the innovation engine that is essential to our economy.”

The open letter was written by Burton Richter, a 1976 Nobel laureate in physics at the Stanford Linear Accelerator Center in California, and organized by the Federation of American Scientists, a private group in Washington. The group is making the letter public on Wednesday.

The Nobel laureates said their concern was not for themselves, since they would have the upper hand in any competition for scarce federal dollars, but for younger scientists who might be poised to produce the breakthroughs of tomorrow.

“We urge you,” they wrote Congress, “to keep the budgets of the agencies that support science at a level that will keep the pipelines full.” The next generation, they added, will determine “our economic vitality” in the future.