WASHINGTON (Reuters) - The U.S. Senate on Thursday confirmed the nomination of John Sullivan, President Donald Trump’s pick to be Ambassador to Russia, at a time when ties between Washington and Moscow have been strained.

FILE PHOTO: U.S. Deputy Secretary of State John J. Sullivan arrives at the Lopez Palace in Asuncion, Paraguay September 6, 2019. REUTERS/Jorge Adorno

Sullivan, a lawyer who has served in previous Republican administrations before becoming deputy secretary of State in 2017, will replace Jon Huntsman, who resigned in August after two years in the post amid speculation that he will run for Utah governor.

Sullivan will be the top U.S. diplomat in Russia at a particularly challenging time in the bilateral relationship, which is strained over a number of disagreements on Ukraine, the Syrian civil war and Iran’s influence in the Middle East, on top of U.S. allegations of Russian meddling in American elections.

Moscow denies the allegations.

Russia’s blossoming ties with China is also a source of concern for U.S. policymakers.

Sullivan’s confirmation also comes at a critical time in Trump’s presidency, which has been shaken by an impeachment inquiry in which Democrats are accusing him of abusing his power by trying to force Ukraine to investigate political rival Joe Biden.

Former Vice President Biden is a leading contender for the Democratic nomination to run against Trump next year.

On Thursday, U.S. lawmakers moved closer to impeaching Republican Trump, as members of a Democratic-led House of Representatives committee debated formal charges likely to be sent to the full House for a vote next week.

Sullivan’s confirmation follows a visit earlier this week by Russian Foreign Minister Sergei Lavrov to Washington, where he met with his U.S. counterpart, Secretary of State Mike Pompeo, and Trump.

The visit has revived allegations of Russian interference in the 2016 U.S. election that resulted in Trump’s upset victory, and whether it might do so again in 2020. Trump warned Moscow against meddling during the meeting with Lavrov, according to the White House and Pompeo.

U.S. intelligence agencies concluded that Russia interfered in the 2016 presidential election.

To replace Sullivan as the next deputy secretary of state, Trump in October nominated Stephen Biegun, the U.S. Special Representative for North Korea, a widely respected foreign policy veteran.

He enjoys broad support and is regarded as an acceptable acting secretary of state by senior current and former U.S. diplomats should Pompeo choose to step down to run for a Senate seat next year.