WASHINGTON - U.S. President Donald Trump confirms that Deputy Secretary of State John Sullivan "could very well be" his choice to be the next U.S. Ambassador to Russia. Trump answered a question from reporters at the White House Tuesday, after media reports said he intends to nominate Sullivan to be one of the most important and challenging U.S. ambassador positions.

Earlier this month, U.S. Ambassador to Russia Jon Huntsman submitted a letter of resignation after two years in his post, calling it a "historically difficult period in bilateral relations." Huntsman leaves the job Oct. 3.

Sullivan has been Deputy Secretary of State since May 2017, after the Senate confirmed him by a resounding vote of 94-6. He briefly led the State Department in the period between former Secretary of State Rex Tillerson's departure in March 2018 and Mike Pompeo's swearing-in April 2018. Sullivan is a lawyer with a long history of federal service, dating back to 1991. He was also the chairman of the U.S.-Iraq Business Dialogue during the Obama administration.

If nominated and confirmed, he would replace Jon Huntsman. In his resignation letter, Huntsman had some advice for his successor, saying, 'Going forward, we must continue to hold Russia accountable when its behavior threatens us or our allies.'

Huntsman has served his country as an ambassador to Russia, China and Singapore under Democratic and Republican administrations, and as the governor of his home state of Utah. Some reports say he may be considering another run for governor there.

His departure comes at a time of a violent crackdown on anti-Kremlin protests, led by supporters of opposition party candidates barred from running for Moscow's city council.

Russian police have detained more than 1,000 people in recent Saturday protests, and images of police beating citizens lying on the ground have captured global attention.

In his resignation letter, Huntsman called on Russia to respect the rule of law and human rights.

In the Oval Office with the Romanian President Tuesday, Trump said he would like for Russia to re-join the Group of Eight leading industrialized countries, which is now the G7. Trump said:

"If somebody would make that motion, I would certainly be disposed to think about it very favorably."

The decision to exclude Russia from the G-8 was made in 2014 by a majority of member countries after Russia's annexation of Crimea.