U.S. Ambassador to Russia Jon Huntsman is resigning from his post effective Oct. 3, according to a letter first reported by the Salt Lake Tribune.

Why it matters: Huntsman is a two-term governor of Utah and former ambassador to China under President Obama who was diagnosed with cancer last year. His resignation is fueling speculation that he may again run for governor of Utah, per the Tribune. Huntsman faced calls to resign after the Trump-Putin summit in Helsinki last summer, but said he would stay on out of commitment to his colleagues and country in this "fragile" era of U.S.-Russia relations.