Last year, Senator Christopher Murphy decided it was time to resort to a filibuster about the need to control the nation’s relentless gun violence. With the help of colleagues in the Senate chamber, he spoke for 15 hours. Nothing changed.

This year, the Connecticut Democrat, sounding even more desperate, tried political candor: “I wish it didn’t feel like Groundhog Day — but one day it won’t,” Mr. Murphy insisted after the Las Vegas gun rampage left 58 dead and many more wounded last month. “There’s no great social change movement in this country that didn’t have failures before it had success,” he said of his perennial proposal, perennially rejected, for tighter background checks on gun buyers.

In the Capitol, no one more clearly epitomizes the Groundhog Day image of dogged persistence in the face of repeated rejection than Senator Dianne Feinstein. The California Democrat responded to the Texas massacre last week (26 dead) by once more introducing her signature proposal to revive the federal ban on rapid-fire assault weapons adapted from the military battlefield. Resolute as Sisyphus, she had helped pioneer and steer to passage a 1994 ban with a 10-year life (the result of a compromise) that the equally dogged National Rifle Association successfully blocked when the time came for renewal.

Had the earlier ban survived, and her fellow legislators showed the same gumption in the face of the gun lobby’s threats, the sorts of military-style, semiautomatic weapons brandished to spray death in Las Vegas and Texas would have been banned. Now she’s back again, ignoring Groundhog Day with a passion that was ignited in 1978 when, as president of the San Francisco Board of Supervisors, she was the first on the scene when two colleagues — Supervisor Harvey Milk and Mayor George Moscone — were shot to death by an assassin.