Sen. Ted Kennedy (D-Mass.) is leaving his seat on the Senate Judiciary Committee, which means he's also stepping down from his post as chair of the Immigration, Refugees and Border Security subcommitee.

Without addressing the issue directly, in the statement he released, Kennedy -- who is being treated for a brain tumor -- said the decision wasn't about his health:

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. This is the opportunity of a lifetime, and I intend to make the most of it.

I also support Sen. Reid's initiative to have senior members of the Democratic Caucus reduce their committee assignments in order to provide opportunities for less senior Democratic senators.

For all of these reasons, I have decided to step down from the Senate Judiciary Committee. I do so with great confidence in Chairman Leahy and my current colleagues on the Committee -- and in the newly elected Democratic senators who will reap new opportunities from my stepping down.

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

Obviously, most people will immediately think of Kennedy's health as a reason for the move, but there's reason to credit his explanation. The desire to restrict commitee assignments was also cited in the decision Senate Democrats made about Sen. Joe Lieberman (I-Conn.). Plus, Kennedy is passionate about reforming health care, and the Clinton administration's experience shows that working on that issue is a pretty demanding job all on its own.