William Barr, attorney general nominee for U.S. President Donald Trump, arrives for a Senate Judiciary Committee confirmation hearing in Washington, D.C., U.S., on Tuesday, Jan. 15, 2019.

President Donald Trump's nominee for attorney general, William Barr, on Tuesday singled out China as the United States' "primary rival," casting Russia as a much smaller threat by comparison, even while acknowledging the Kremlin's attempts to sway the 2016 U.S. election.

Barr's testimony, delivered at his confirmation hearing before the Senate Judiciary Committee, followed a slew of questions about the scope and authority of special counsel Robert Mueller's ongoing probe of Russia's election interference and possible collusion with the Trump campaign. His threat assessment also came amid the Trump administration's high-level trade talks with Beijing, which have kept global markets on edge for more than a year.

Asked by Republican Sen. Ben Sasse of Nebraska whether Russian President Vladimir Putin was a friend or a foe, Barr first said that "I think the Russians are a potent rival of our country."

But "at the same time, I think the primary rival of the United States is China," Barr added.

"Russia is half the size it was when we were facing them at the peak of the Cold War. Their economy's long-term prognosis is nowhere near China's," he said.

"I'm concerned that the fixation on Russia not obscure the danger from China."

Asked if he had reason to doubt National Intelligence chief Dan Coats' assessment that Russia is already plotting to interfere in the 2020 presidential election, Barr said, "I haven't seen those reports," but "I have no reason to doubt it."

Barr highlighted China as America's biggest rival as trade talks between the two nations appeared to stall on key issues, Sen. Chuck Grassley, R-Iowa, said in a conference call Tuesday.

U.S. Trade Representative Robert Lighthizer said "there hasn't been any progress made on structural changes that need to be made," according to Grassley.

Trump has been roundly criticized for his friendly approach to Putin in light of U.S. intelligence conclusions about Russia's interference in America's democratic process. NBC News reported Tuesday that Trump has treated his meetings with Putin more protectively than his interactions with other world leaders.

But Trump has consistently attacked China for its allegedly unfair trade practices, including the long-term alleged theft of U.S. intellectual property.