A surge in homicides, propelled in part by a tightening of drug supplies and the proliferation of high-powered semiautomatic weapons, threatens to make this year the most murderous in American history, according to a Senate Judiciary Committee report released yesterday.

A state-by-state analysis showed an increase in murders across the country: 17 percent in Virginia, 19 percent in New York, 22 percent in Massachusetts and Washington state and 50 percent in Idaho.

Citing an overall nationwide jump of about 8 percent during the first half of this year, the panel projects that more than 23,220 people will be murdered in 1990 -- about 2,000 more than in 1989 and slightly higher than the national record of 23,040 murders in 1980.

The District, which last year had the highest per capita homicide rate in the country, has had increases in line with the national average. After homicides dipped slightly earlier this year, police have reported a steady succession of murderous weekends this summer. So far, 273 people have been killed in the city this year, compared to 250 at the same time last year when the city hit an all-time high of 434 murders.

"The nation is faced with an immediate peril and the situation is doomed to get worse unless we take action today," said Sen. Joseph R. Biden Jr. (D-Del.), the committee chairman, during a hearing on the issue. He called for an "all-fronts assault on the drug epidemic" as well as swift House passage of a Senate-passed crime bill that would ban domestically manufactured assault weapons and impose the death penalty for 34 federal offenses.

But the report -- and a leading criminologist -- also cited larger demographic trends that are driving the homicide rate and are likely to accelerate it for the rest of the decade.

The nation's homicide rate first soared in the 1960s and 1970s as the post-World War II baby boom generation began to reach their late teens and early 20s -- the age group most prone to violence. But after jumping from 9,110 murders in 1960 to 23,040 in 1980, the number of homicides dropped 17 percent over the next five years as the baby boomers grew older.

But since then, the country has been experiencing what Northeastern University criminologist James Alan Fox called the "baby boomerang effect." The children of the first wave of baby boomers are now starting to reach their late teens, a demographic trend that is expected to continue throughout the 1990s.

As a result, "the worst may yet be to come," warned Fox in testimony before the committee. "This nation should prepare itself for increasing problems of teen crime, teen pregnancy and youth unemployment."

The demographic trends have fed into the two social trends that have hit many urban communities in recent years -- explosive increases in crack cocaine and high-powered semiautomatic weapons, the committee report said.

Hospital emergency rooms are increasingly reporting patients with multiple gunshot wounds -- a sign they have been shot by semiautomatic weapons, said J. Lawrence Cogan, acting chief medical examiner of Los Angeles County, where the murder rate jumped 17 percent during the first six months of the year.

At the same time, the number of "drug related" murders has nearly tripled -- from 509 in 1985 to 1,402 in 1989, according to FBI figures due out later this week. This is still less than 7 percent of the overall total, although committee staff members say the FBI figures may understate the role of drugs because they do not count murders involving disputes over drugs, only those committed under the influence of drugs.

Nevertheless, the panel concluded that this year's increases are being fueled by a development the Bush administration has recently cited as a measure of progress in the drug war -- a tightening of supplies that has led to sharp increases in cocaine prices and diminished purities in the streets.

In Boston, for example, where the number of homicides has soared 58 percent through July, higher cocaine prices have led to more "drug dealers ripping off drug dealers" and an 18 percent jump in drug-related murders, said Joseph Saia, chief of detectives of the Boston police.

"I would say there's a direct correlation," Saia said in an interview. Moreover, as the drug situation improves, "you're going to see more violence," he said.