One of science's most dogged advocates in Congress will be retiring at the end of this term. Rep. Rush Holt (D-N.J.), the former assistant director of Princeton's plasma lab, announced Tuesday that he will not seek another term.

Holt was originally elected in 1998 -- and since has become well known for his "My Congressman IS a Rocket Scientist" bumper stickers and defeat of IBM supercomputer Watson in an exhibition match on "Jeopardy." (Holt also appeared on the actual show before he was elected, winning five times.)

He has been a major proponent of science funding. "My science training is good problem-solving training, but there are also matters that come before Congress that have scientific or technical components that get very little attention," he told Popular Science in a 2008 interview.

"A lot of people think we need scientists to deal with the science issues—the funding for NASA and things like that. I'm not worried about that. It is the countless other things that come before us that have scientific components that are ignored."

Holt was also active on other issues related to science and technology. He was a leading advocate for legislation improving the reliability and security of electronic voting machines. And he advocated the repeal of the USA PATRIOT ACT and the FISA Amendments Act; his proposal would have undermined the legal foundation for many NSA domestic spying programs

Holt is the son of former West Virginia senator Rush D. Holt (D-WV) and made a Senate bid in a New Jersey special election last year, but lost in the primary to now-Sen. Cory Booker (D-NJ).

There were once three physicists in Congress. But after Holt retires, it appears Rep. Bill Foster (D-Ill.) will be the lone physicist left in Congress.