President Clinton will propose a $3,000 tax credit for families that provide long-term care for a seriously ill member, three times the amount he proposed last year, White House officials said yesterday.

The plan, which would cost $28 billion over 10 years, would be aimed at about 2 million American families that care for persons with debilitating conditions such as Alzheimer's disease, the officials said. Medicare, the federal health program for the elderly and disabled, does not cover long-term care, and both Democrats and Republicans have said the government should do more to help in that area.

But so far they have failed to agree on a method. Last year, Clinton proposed a $1,000 tax credit for long-term caregivers, and the Republican-led Congress endorsed a plan to help such families buy insurance that covers long-term care. Both proposals fell victim to last fall's budget impasse, when Clinton vetoed a massive GOP tax-cut bill and Congress approved only a small number of his tax initiatives.

Now that congressional Republicans have signaled they won't try another major tax cut bill this year, leaders of both parties say there is hope for goals such as easing the financial burden on long-term caregivers. Administration aides say Clinton decided to triple his proposed tax credit because he believes the need is significant and the tax credit is popular. They also note that Vice President Gore, locked in a presidential primary battle, has touted the idea.

John Rother, legislative director for AARP, said in an interview: "I think it's a realistic proposal in terms of enactment this year." He noted that Republicans called for subsidizing long-term care in their Contract With America, which spearheaded their 1994 takeover of Congress. "If there is agreement on a smaller, more targeted tax cut, this would fit right in," Rother said.

Clinton's proposed tax credit would be phased in, beginning with $1,000 in 2001 and rising by annual increments of $500, so eligible people could receive up to $3,000-a-year by 2005. Many families would not receive the full benefit, however, because they don't pay $3,000 in federal income taxes. The credit would be phased out beginning with couples earning $110,000 a year and individuals making $75,000. Clinton also is proposing more federal money for state and local programs that support long-term caregivers, such as counseling services.

To qualify for the proposed tax credit, the person receiving care must have at least three "limitations in activities of daily living or a comparable cognitive impairment," according to a White House briefing document. Rother said, "It's only for people who are seriously disabled. Slight disabilities aren't going to do it."

Meanwhile, yesterday, Clinton was in Boston to call for $280 million in new spending for a major firearms initiative aimed at strengthening the enforcement of existing laws, improving firearms safety and creating community-based teams to combat gun-related crimes. Joined by Attorney General Janet Reno at the Orchard Gardens housing development in Boston's Roxbury neighborhood, the president said he wants an additional 500 firearms agents and inspectors for the Bureau of Alcohol, Tobacco and Firearms as well as partial funding for the hiring of 1,100 federal, state and local prosecutors across the country to pursue primarily gun-related cases.

"All together, these efforts represent the largest national gun enforcement initiative in the United States," Clinton told more than 400 community activists, police officers and legislators. He praised Boston's efforts in building coalitions and targeting repeat offenders and gun traffickers.

Also in Boston, Clinton spokesman Joe Lockhart said the president believes South Carolina should stop flying the Confederate battle flag above its state capitol.

"He's not saying the Confederate flag per se doesn't have some historical meaning to it," Lockhart told reporters. "But in this case it's wrong and it shouldn't be flown." He said Clinton reminded him that South Carolina began flying the flag in 1962 as a gesture of "defiance" against racial desegregation. On Monday, 46,000 protesters marched in Columbia, S.C., calling for the flag's removal.

Correspondent Pamela Ferdinand in Boston contributed to this report.

CAPTION: In Boston, President Clinton proposes $280 million in new spending for a firearms initiative aimed at strengthening law enforcement, improving firearms safety and creating anti-crime teams.