Lt. Gov. Justin Fairfax (D), top left, and House Speaker M. Kirkland Cox (R-Colonial Heights), right, talk with Virginia Gov. Ralph Northam (D) after the governor’s State of the Commonwealth address in January. (Steve Helber/AP)

Justin Fairfax gets to do two things as Virginia’s lieutenant governor — preside over the state Senate and take over if the governor can’t finish his term.

With Gov. Ralph Northam (D) alive and well, that leaves Fairfax with a largely ceremonial gig in the Senate. He made his biggest splash there by stepping off the dais one day — the first African American elected to Virginia statewide office in a generation, quietly protesting a tribute to Confederate Gen. Stonewall Jackson.

But Fairfax (D), who is widely expected to run for governor in 2021, could soon get an opportunity to make his mark. Depending on how a long-running battle over Medicaid expansion plays out over the next few months, he could have the chance to cast the tiebreaking vote to provide health care eligibility to as many as 400,000 uninsured Virginians.

That would be a profile booster for Fairfax, a former federal prosecutor who had never held elective office. It could come courtesy of Senate Republicans if they remain dug in against expansion, forcing Northam to resort to a hardball tactic involving a budget amendment and a Fairfax tiebreaker.

“Being lieutenant governor is sort of like being the Maytag repairman: Most of the time nobody calls, but when the call comes in, they really, really need you,” said Stephen Farnsworth, a University of Mary Washington political scientist. “It will be the biggest moment in the sun for . . . [any] lieutenant governor in years if this comes to pass.”

Fairfax, 39, said he would welcome the chance to cast the deciding vote.

“Obviously, if we were in a position to break a tie on an amendment that would expand Medicaid, we do it,” said Fairfax, who gave up his job as a litigator for the white-shoe law firm Venable to focus on the lieutenant governorship, a part-time job that pays $36,321 a year.

“It would most importantly be something that would benefit hundreds of thousands of Virginians, finally give them access to needed — in some cases lifesaving — health insurance,” he said. “This is now an economic issue. It is a moral issue, I think, in many ways. And I really would love to see this happen.”

Even if that opportunity does not come Fairfax’s way, he will have had an auspicious, if under-the-radar, start to the lieutenant governorship, said Democrats and Republicans alike. Many are impressed with his mastery of Senate procedures, particularly as someone with no experience in Richmond. Fairfax credits Senate Clerk Susan Clarke Schaar and her staff with helping him prepare.

“He is my seventh lieutenant governor. He’s the quickest study of all of them,” said Sen. Janet D. Howell (D-Fairfax County). “He’s been procedurally flawless, and he has just a captivating sense of humor that sort of gets rid of some of the tension on the floor.”

Senate Minority Leader Richard L. Saslaw (D-Fairfax County) said one would have to go back to Don Beyer, now a congressman who leaped from auto dealer to lieutenant governor 28 years ago, to find another newcomer who wielded the Senate gavel so deftly.

“He’s got terrific rapport with both sides of the aisle,” said Sen. Richard H. Black (R-Loudoun), perhaps the Senate’s most conservative member.

One exception to the amicability came in February, when Senate Majority Leader Thomas K. Norment Jr. (R-James City) scolded Fairfax for requiring a recorded vote after declaring a voice vote too close to call. Norment sarcastically suggested Fairfax was hard of hearing.

“Well, I’m not hearing-impaired,” Fairfax shot back. “And I was uncertain. So I will do a recorded vote when it’s necessary.”

Fairfax’s working relationship with Northam does not appear to be as tight as some recent governor-lieutenant duos — something some political observers say could be a sign that Northam, constitutionally prohibited from serving back-to-back terms, might prefer another successor. Another possible Democratic contender is Richmond Mayor Levar Stoney, who was secretary of the commonwealth under Northam’s predecessor and political patron, Terry McAuliffe (D).

Northam spokesman Brian Coy dismissed such speculation as premature.

“Given that he’s still in the first half of the first year of his own governorship, that’s a crazy question for you to ask,” Coy said. “The governor values the professional and personal relationship he has with Lt. Gov. Fairfax, and is looking forward to accomplishing a great deal with him over the course of this term.”

Because the state constitution gives the lieutenant governor little to do, governors often provide lieutenants extra, résumé-boosting duties if they are political allies. But they are not always allies, or even members of the same party, because the governor and lieutenant run independently in Virginia.

When Northam was lieutenant governor, he or his chief of staff regularly attended McAuliffe’s Cabinet meetings. McAuliffe also appointed Northam to his Children’s Cabinet, focused on policies affecting youths in the commonwealth. McAuliffe’s predecessor, Robert F. McDonnell (R), made then-lieutenant governor Bill Bolling (R) a member of his Cabinet, naming him chief job creation officer.

Fairfax has not been attending Northam’s Cabinet meetings or been given any formal role in the administration, something the lieutenant governor attributed to the hectic start to the new year. He said he and Northam have been looking for ways to “work hand-in-hand.”

“Justin and Ralph worked very well together during the session and have a close personal relationship,” said Fairfax spokeswoman Lauren Burke. “Now that the session is over, they will sit down and talk more about what they’ll do together moving forward.”

Northam credited Fairfax with helping to advance his agenda.

“This session we made great progress on a number of issues that are important to the people of Virginia and we couldn’t have done it without Justin Fairfax’s leadership,” Northam said via email. “He is a thoughtful and energetic leader for this Commonwealth and I am thrilled to have him as a partner.”

Whatever opportunities Northam provides Fairfax as they settle into their offices, they are unlikely to top the one Senate Republicans might inadvertently hand him with Medicaid.

Virginia’s GOP-controlled legislature staunchly resisted expanding the federal-state health-care program for four years under McAuliffe. Opposition softened in the House after Democrats ran on a pledge to expand Medicaid and nearly won control of the chamber in November elections. But the Senate, which did not face voters last year, has remained opposed, predicting that the federal government will not keep its promise to pick up at least 90 percent of the $2 billion-a-year expansion tab.

The impasse kept the legislature from passing a two-year budget before adjourning March 10. The state needs a spending plan in place by July 1 to avoid a government shutdown.

Not much has changed since March, despite the kickoff of a special session on the budget two weeks ago and declarations from two Senate Republicans, Emmett W. Hanger Jr. (Augusta) and Frank W. Wagner (Virginia Beach), that they would support expansion under certain conditions. The House has passed a new budget bill that is essentially the same as its original. The Senate announced this week that it will not return to Richmond to consider it until May 14.

It would take just two Republicans to pass expansion on a budget vote in the Senate, which Republicans control 21-19. But it could be tricky to satisfy both Hanger and Wagner because some of their conditions conflict.

So Northam might be forced to take another route that requires support from just one Republican, creating a 20-to-20 tie that Fairfax could break. That would have to happen on a budget amendment — the lieutenant governor would be allowed to vote on that but not on the budget itself.

While going the amendment route would be a political plus for Fairfax, others see a downside. Northam, who ran as a consensus builder, would rather not have something as consequential as Medicaid expansion squeak through on the barest majority. Some Republicans would rather not give Fairfax that win.

“I like the lieutenant governor fine, but I’m not going to have him resolve this for us,” Hanger said. “We need to resolve it ourselves.”