JEFFERSON CITY — Sen. Kit Bond plans to announce Thursday that he will not seek re-election in 2010, according to high-ranking Missouri Republicans.

Bond was expected to make the announcement shortly after Missouri lawmakers convene at 10 a.m. in the state Capitol. The sources spoke on condition of anonymity to avoid upstaging Bond's planned announcement.

Bond, 69, first was elected to the Senate in 1986 — the only Republican to capture a seat previously held by a Democrat that year. Missouri voters have re-elected him three times since, and as recently as a few months ago, Bond had told crowds that he would be seeking re-election to a fifth Senate term.

Bond's retirement is the second political jolt to the Missouri Republican Party in as many years.

In January 2008, Republican Gov. Matt Blunt stunned supporters and foes alike by announcing he would not seek a second term. A contentious two-way Republican primary resulted, and Democrat Jay Nixon ultimately won the governorship in the November general election.

Bond, a native of rural Mexico, Mo., has been the most consistent face of the Missouri Republican Party for several decades.

After serving briefly as an assistant attorney general under John Danforth, Bond was elected state auditor in 1970. At age 33, Bond became Missouri's youngest governor when he was sworn into office on Jan. 8, 1973 — exactly 36 years before Thursday's announcement of his political retirement.

Bond lost re-election in 1976 only to rebound and win a rematch against Democratic Gov. Joe Teasdale in 1980.

In the Senate, Bond is known as a workhorse who relished the increasing clout he wielded. He became vice chairman of the Intelligence Committee in late 2006 and later played a key role in bringing both parties together to revise the 30-year-old Foreign Intelligence Surveillance Act, a feat he considered one of his greatest accomplishments as a lawmaker.

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