Massachusetts Democrat Edward M. Kennedy announced Friday that he is giving up his seat on the Senate Judiciary Committee in the 111th Congress to concentrate on major health care legislation.

“As chairman of the Senate Health, Education, Labor and Pensions Committee, I expect to lead a very full agenda in the next Congress, including working with President Obama to guarantee affordable health care, at long last, for every American,” Kennedy said. “This is the opportunity of a lifetime, and I intend to make the most of it.”

Kennedy has been a major force in shaping civil rights, immigration and criminal justice legislation since joining the committee in 1963 shortly after he was first elected to the Senate. He was chairman during the 96th Congress (1979-81), and now is chairman of the Judiciary Subcommittee on Immigration, Border Security and Citizenship.

Lawmakers, including Kennedy, unsuccessfully attempted to pass comprehensive immigration legislation during the 110th Congress. That issue has slipped down the congressional priority list, behind health care and legislation related to financial aid for the worsening U.S. economy.

“I remain deeply committed to civil rights, equal opportunities and immigration reform, and I will always be involved in those important debates and discussions,” Kennedy said.

One top Kennedy aide described the health care overhaul as “priority one, two and three” for the veteran Massachusetts Democrat. Kennedy has been sidelined and largely out of view since being diagnosed with brain cancer in May. He has recently returned to work in the Senate, and aides say that he will be back full-time in January.

Kennedy has been coordinating with the Obama team on health care overhaul plans, and working closely with other Democrats, such as Senate Finance Chairman Max Baucus , D-Mont. Aides to Kennedy and Baucus have met repeatedly and are planning to produce a health care plan early in the 111th Congress, either separately or under the “one bill” approach Kennedy has been pushing.

Kennedy said he supports an effort by Senate Majority Leader Harry Reid , D-Nev., to enforce a Senate rule preventing full committee chairmen from having more than one subcommittee gavel. Reid wants to make room for the incoming Democratic freshmen.

Kennedy said he is leaving Judiciary “with great confidence in Chairman (Patrick J.) Leahy (D-Vt.) and my current colleagues on the committee – and in the newly-elected Democratic senators who will reap new opportunities from my stepping down.”

Kennedy is keeping his seat on the Senate Armed Services committee, and his chairmanship of its Seapower subcommittee, according to an aide.

“Ted has always been a giant on the committee,” Leahy said. “I will miss his wise counsel, but am thankful that we serve together in the Senate.”

In the 110th Congress, the committee had 10 Democrats and nine Republicans. That ratio may change, given the increased size of the Senate Democratic majority. Vice President-elect Joseph R. Biden, Jr., D-Del., was another senior Democrat on the panel.

Leadership aides have said negotiations between Reid and Minority Leader Mitch McConnell over how many more seats Democrats get on committees than Republicans might not be complete until after all the outstanding Senate races are decided. With this week’s Georgia runoff keeping one contested seat in Republican hands, the only outstanding race is Minnesota, where incumbent Republican Norm Coleman continues to hold an edge over Democrat Al Franken.