Senators Lamar Alexander (R-Tenn.) and Tim Kaine (D-Va.) practice ahead of a musical performance on the Tennessee and Virginia state line this Friday. (Whitney Shefte/The Washington Post)

What do you call two senators from different parties who plan to perform together at a concert?

The Amateurs.

That’s the band name Sens. Lamar Alexander (R-Tenn.) and Tim Kaine (D-Va.) are using Friday for a one-night-only performance at the Rhythm & Roots Reunion in Bristol — a city in southwestern Virginia or northeastern Tennessee, depending on where you’re standing.

Alexander and Kaine represent either side of the town and are the states’ former governors. They both strike a moderate tone on Capitol Hill and are well liked by members of both parties, with whom they frequently collaborate. They’re also accomplished musicians.

Given that common bond, is their upcoming concert the key to restoring bipartisanship in Washington? Maybe.

After all, Alexander leads the committee responsible for salvaging health-care legislation, and Kaine is a member. Alexander has tried to negotiate deals to keep the Senate from overhauling its procedural rules, and Kaine wants to strike a bipartisan deal on when Congress declares war.

For now, let’s just admire their musicality.

Alexander, 77, is a skilled piano player who has used his keyboard prowess throughout his political career. During his failed 1996 presidential campaign, “I played all over Iowa,” he recalled. “I’ve sung the ‘Tennessee Waltz’ in every little town in Iowa. It didn’t really work.”

Kaine, 59, is a self-taught harmonica player who picked up the habit and began playing publicly during his 2005 gubernatorial bid.

The pair discovered each other’s musical talents in 2014 thanks to another senator, Ted Cruz (R-Tex.), when he forced a rare Saturday voting session just a few days before Christmas. During the all-day ordeal, Sen. Amy Klobuchar (D-Minn.) had her electric keyboard wheeled into the Capitol so colleagues could play Christmas carols. Sen. Robert Menendez (D-N.J.) was among those who sang, while Sens. Debbie Stabenow (D-Mich.) and Thad Cochran (R-Miss.) took turns at the keyboard. Eventually, Sen. Roger Wicker (R-Miss.) went to find Alexander. “Thad’s run out of songs,” Wicker told him. “Can you come and play some more?”

Kaine was there with his harmonica, and the two discovered a mutual interest. During a recent visit to East Tennessee with their wives, they agreed to perform at the festival Friday.

Neither man is a stranger to performing for voters. Kaine performed on “The Late Show With Stephen Colbert” last year while campaigning to be vice president. In addition to playing piano for voters back in 1996, Alexander has performed at anniversary concerts for the Great Smoky Mountains National Park and did concerts with community orchestras and symphonies when he was governor in the 1980s.

“People came to see the governor make a mistake on the piano, and it worked out great,” Alexander said.

He’s also used his talent to his legislative advantage. Cochran, chairman of the Senate Appropriations Committee, keeps a baby grand piano in his office. “Every time I go down to see him,” Alexander said, “I play him a little song before I ask for my appropriation allocation.”

Kaine carries seven harmonicas with him: “Keys A through G. So they can say, ‘We’re playing it in D.’ Okay, I’ll find the D and I’ll play in D.”

“I have the reverse problem,” Alexander deadpanned. “When I show up  in Tennessee, they usually move the piano out of the room and make sure I don’t play for them.”

Bristol, where they’ll perform Friday, is called the “Birthplace of Country Music” and is home to a museum dedicated to the cause. This headliners for this year’s festival include Dwight Yoakam, and Alexander and Kaine are set to perform at the opening event along State Street, which runs along the state line.

To perform, they needed a name, so Kaine came up with four options and gave his more senior colleague the right to choose.

The Capitol Hillbillies? The Bluegrass Roots? Two-System Party?

“My personal favorite was Two-System Party,” Kaine said, but Alexander demurred. “The fourth one I put on the list was the Amateurs, and Lamar goes, ‘That’s the one.’ And I said, ‘Why do you like that one?’ And he said, ‘You’ve got to set expectations.’ ”

Their set will include old-time country, gospel and bluegrass classics: “Turn Your Radio On,” “Keep On the Sunny Side of Life,” “I Saw the Light” and Alexander’s signature song, “Tennessee Waltz.” (Alexander performed the song with Patti Page at a recording session in Nashville in 2013.)

They rehearsed in shirt sleeves, with Kaine standing next to the brown Baldwin piano wheeled into Alexander’s office for the rehearsals. A gold plaque on the piano says it was presented to Congress in 1966 by the American Society of Composers, Authors and Publishers. Alexander said it had needed a good tuning before they rehearsed.

Anyone who happened to walk down the hall on the fourth floor of the Dirksen Senate Office Building might have heard the music.

Keep on the sunny side, always on the sunny side
Keep on the sunny side of life
It will help us every day, it will brighten all the way
If we keep on the sunny side of life

After the concert Friday, Kaine is performing at a wedding of a family friend Saturday. He’s playing with his church’s gospel choir at a 40th-anniversary concert next week and at a Richmond event later in September.

“The one thing I’ve learned is, it’s hard to not think about work,” he said. “But if I play music, I’m not thinking about work.”

Alexander started playing piano at age 3 and looks just as in command at the keys as he is on a committee-room dais. He began by learning classical music and quickly learned how to play more-popular tunes.

“I was trained to play classical music, but I would goof off,” he said. “My music teacher would say: ‘Okay, your left hand is jumping all around. You’ve been playing that Jerry Lee Lewis stuff again.’ ”

As the rehearsal ended, he played four bars of “Tennessee Waltz” for reporters:

I was waltzing with my darlin’ to the Tennessee Waltz
When an old friend I happened to see
I introduced him to my loved one
And while they were waltzing
My friend stole my sweetheart from me

So will this be a regular gig? Could they take over open-mic night at a Washington speakeasy?

“We’ll take it a step at a time,” Alexander said.

With that, the two senators exited into an adjoining room to strike up a conversation about legislation.

Who knows? Maybe music is, in fact, the key to bipartisan dealmaking.