U.S. Rep. Rush Holt has decided not to run for a ninth term representing Central Jersey's 12th District.

A five-time champion on "Jeopardy!" and a research physicist by trade, Holt has advocated research funding and environmental protection.

Holt, a Democrat, is the third member of New Jersey's congressional delegation to decide not to seek re-election.

That represents a great deal of loss, said Ben Dworkin, a political science professor at Rider University.

"New Jersey is losing a tremendous amount of seniority and that's going to make it that much tougher to rally support and leverage for funding for the things that New Jersey needs," Dworkin said Tuesday. "Things like beach replenishment, additional Sandy aid, and transportation infrastructure funding."

Holt's decision was unexpected, said Fairleigh Dickinson University political science professor Peter Woolley.

"I am surprised by this. I talked with him in his office a few weeks ago," Woolley said. He did express frustration, but nothing he said suggested to me that he was going to decide not to run again."

Holt has not said what he plans to do after leaving Congress.

Analysts say voters in the district are likely to elect another Democrat to replace him.