SACRAMENTO (AP) — Republican state Sen. Bill Emmerson announced Friday that he is resigning in midterm, citing his waning enthusiasm for a job he has held since 2010.

His resignation will take effect Dec. 1, according to a statement posted on his official website and confirmed by spokesmen for Senate President Pro Tem Darrell Steinberg.

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“It is with disappointment that I receive Senator Emmerson’s resignation,” Steinberg said in a statement. “Bill is a valued colleague and I appreciate his contributions to the Senate and the State of California. I wish him all the very best in his future endeavors.”

Emmerson, 68, of Redlands, has represented his Southern California district since 2004, when he was elected to the Assembly. He won his Senate seat in 2010, and would have been forced out of office by term limits in 2016.

His resignation sets up a special election but is not expected to change the composition of the Senate, where Democrats hold a two-thirds supermajority.

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Republicans have 41 percent of registered voters to Democrats’ 34 percent in the district that includes parts of Los Angeles, Riverside and San Bernardino counties.

“In these past few months, my passion has waned and my constituents deserve a Senator with the level of commitment that I once had,” Emmerson said in the statement.

He called his nine years of service “some of the most fulfilling years of my life” and “an honor” but said it is time to move on. He said he remains in perfect health.

Mark Hedlund, spokesman for Steinberg’s office, said it came as a surprise when Emmerson submitted his resignation Friday afternoon.

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