Jon Huntsman, the Trump administration’s ambassador to Russia, resigned Tuesday amid chatter he may return home to run again for governor of Utah, Fox News has confirmed.

The news was first reported by The Salt Lake Tribune, which posted a copy of Huntsman’s resignation letter to President Trump. He said his resignation will take effect Oct. 3.

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“American citizenship is a privilege and I believe the most basic responsibility in return is service to country,” Huntsman said in the letter to Trump. “To that end, I am honored by the trust you have placed in me as the United States ambassador to Russia during this historically difficult period in bilateral relations.”

The posting in Russia was Huntsman’s third as ambassador: he also served as ambassador to Singapore from 1992 to 1993 and ambassador to China from 2009 to 2011. In his letter, Huntsman urged Trump to take a firm stance with Russia: “Going forward, we must continue to hold Russia accountable when its behavior threatens us and our allies,” he said.

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Huntsman, who unsuccessfully ran for president as a Republican in 2012, previously served as governor of Utah from 2005 to 2009. The Salt Lake Tribune cited “people close” to Huntsman in saying he considering another gubernatorial run in Utah.

Huntsman is the father of former "Fox & Friends Weekend" co-host Abby Huntsman.

Fox News’ John Roberts contributed to this report.