WASHINGTON >> The Republican-led Congress is moving swiftly to clear the way for retired Gen. James Mattis to run the Pentagon, winning support from Democrats who believe he’ll be a bulwark to a president-elect they fear will carry his impulsive, bombastic style into the White House.

The support underscores concerns over Donald Trump’s dearth of military and foreign policy experience as well as the bipartisan respect Mattis cultivated on Capitol Hill during his 44 years in the military.

The House on Friday is expected to pass legislation that would override a legal barrier preventing Mattis from becoming Trump’s defense secretary. The bill would then be sent to the White House.

It was unclear if President Barack Obama would sign the legislation, or if it would fall to Trump after his inauguration.

The Senate cleared a similar measure easily, 81-17, after 30 Democrats including Sen. Martin Heinrich of New Mexico backed the bill. The legislation is separate from a Senate confirmation vote on Mattis, but it signals there will be no real hurdle to approving Trump’s choice shortly after the president-elect is sworn in next week.

Heinrich said Thursday that lawmakers needed to consider “the temperament of the incoming White House team” in deciding whether to grant an exception to the law that bars former service members who have been out of uniform for less than seven years from holding the top Pentagon job. The restriction is meant to preserve civilian control of the military. Mattis retired from the Marine Corps in 2013.

Heinrich asked Mattis during his Armed Services Committee confirmation hearing to assure lawmakers he would provide “sound policy and guidance” to Trump, especially regarding the possible use of nuclear weapons.

Sen. Jack Reed of Rhode Island, the committee’s top Democrat, also backed the waiver legislation because Mattis would act as a “counterbalance” to Trump. Reed said many Americans are rightly concerned about how Trump may respond when he is tested by Russia, Iran or North Korea, or faces a cyberattack from an unknown source.

Reed called Mattis a “generational exception.”

Mattis faced no hostile questions during the hearing. He called Russia the nation’s No. 1 security threat and accused its leader, President Vladimir Putin, of trying to “break” NATO.

He described Iran as a major destabilizing force, called North Korea a potential nuclear threat and said the U.S. military needs to be larger and more ready for combat.

“We see each day a world awash in change,” Mattis said. “Our country is still at war in Afghanistan and our troops are fighting against ISIS and other terrorist groups in the Middle East and elsewhere. Russia is raising grave concerns on several fronts, and China is shredding trust along its periphery.”

Mattis portrayed Russia as an adversary and said the history of U.S.-Russian relations is not encouraging.

“I have very modest expectations for areas of cooperation with Mr. Putin,” he said, delivering an assessment very different from that of his potential commander in chief. Trump has repeatedly praised Putin, even as U.S. intelligence agencies have accused the Russian leader of orchestrating a campaign of interference in the 2016 U.S. election.

“He is trying to break the North Atlantic alliance,” Mattis said of Putin.

He said he has explained to Trump his views on Russia, which include a deep worry that Moscow is determined to use intimidation and nuclear threats to create a sphere of unstable states on its periphery.

Mattis, who has served in numerous senior military positions, including commander of U.S. Central Command in charge of all American forces in the Middle East, said he supports the Obama administration’s moves to reassure European allies after Moscow’s annexation of Ukraine’s Crimea region and military activity in eastern Ukraine.

While the U.S. should remain open to working with Russia, Mattis said, the prospects for cooperation were narrowing even as areas of disagreement grow larger.