WASHINGTON — At a quarter till midnight last Friday, with a deal to avert a government shutdown barely an hour old, Senator Harry Reid phoned a fellow Democratic senator, Ron Wyden, at home and startled him with some bad news. “You lost free-choice vouchers,” Mr. Wyden recalls Mr. Reid telling him.

Even delivered in shorthand, the call’s meaning was clear to Mr. Wyden: a health care plan he had succeeded in getting passed months earlier despite furious lobbying by big business and labor had been pulled out of the blue and killed as part of the broader budget deal struck between the White House and Congress. What was most perplexing was that it had little to do with budgets or government shutdowns.

“I was flabbergasted, just flabbergasted,” Mr. Wyden, of Oregon, said Tuesday in an interview, describing the demise of a plan that would have allowed some 300,000 workers to pick their own insurance coverage through employer-financed vouchers.

With $38 billion in cuts on the line in a $3.5 trillion budget, the clash over federal spending played out in numbers so big that most standard calculators had trouble tracking all the zeros. But in the end, a handful of relatively small-bore line items affecting particular industries attracted some of the most aggressive lobbying behind the scenes, as business interests, health care providers and others fought to hold on to, or kill, proposals that affected their bottom line.