Complex sentence: Brinegar was nominated to the post of United States Secretary of Transportation by Richard Nixon, he also served under Gerald Ford but when Ford said he intended to seek the Presidency, Brinegar resigned and returned to an executive position at Union Oil.
Split into simpler sentences: Brinegar was nominated to the post of United States Secretary of Transportation by Richard Nixon. He also served under Gerald Ford, but when Ford said he intended to seek the Presidency, Brinegar resigned and returned to an executive position at Union Oil.