Updated February 25 at 9 a.m.

After nearly 36 years in Congress, Oklahoma Republican Sen. Jim Inhofe plans to announce Monday he will resign at the end of the year, triggering a special election this November for his seat, a source close to the senator told the Cook Political Report.

The 87-year-old Inhofe had achieved his longtime goal of chairing the Senate Armed Services Committee following the death of Arizona Sen. John McCain, but was demoted to ranking member last year after Democrats won control of the chamber. While Inhofe could regain the post if Republicans flip control, ultimately, the source said the decision isn’t because of any illness but simply a desire to return to Oklahoma to spend time with his family and grandchildren.

Inhofe first got his start in politics in 1966 after he was elected to the Oklahoma House and later the state Senate. He earned his degree from the University of Tulsa after having delayed his education to serve in the Army. He was also elected the mayor of Tulsa in 1978, and

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