ATLANTA — National Democrats will elect a new chair whose task is to steady a reeling party and capitalize on the widespread opposition to Republican President Donald Trump.

Leading contenders in the Saturday vote are former Labor Secretary Tom Perez and Minnesota Rep. Keith Ellison. Mayor Pete Buttigieg of South Bend, Indiana, is a longshot hoping he can rise to the top if neither of the two front-runners can capture majority support from the Democratic National Committee.

Here’s an explanation of why an election among party insiders has drawn so much attention.

WHAT DOES THE PARTY CHAIRMAN DO?

The chair is the Democratic National Committee’s top executive. Outgoing Chairwoman Donna Brazile says her successor “must be fearless … must have courage,” but there’s no absolute job description.

The post is part cheerleader, part fundraiser, part organizer and recruiter, part public messenger. It’s a much more visible role when a party no longer occupies the White House, since the president is de facto leader of his own party. Presidents also name their own party chairs, with the national committee operating essentially as a political arm of the Oval Office. The losing party’s chair, though, is elected by its national committee members.

Ellison, Perez and Buttigieg have all committed to oppose the Trump administration with gusto, but concentrate on nuts-and-bolts rebuilding of party infrastructure that helps win elections.

The new chair won’t be an undisputed “leader of the party.” Senate Minority Leader Chuck Schumer of New York and House Minority Leader Nancy Pelosi of California will remain the highest ranking Democrats in Washington, but the DNC chair will play a major role in framing the party’s arguments and identity, while charting a strategy to turn those into votes in upcoming elections.

WHY DOES IT MATTER SO MUCH THIS TIME?

Neither major party has had such a competitive chair election in recent history, but there’s a reason for Democrats’ existential lurching: They have as little actual political power around the country as they’ve had in 90 years. That means virtually no American voter has ever seen Democrats so removed from controlling the nation’s policies.

Republicans run both houses of Congress, sit in 33 governor’s chairs, control 32 state legislatures and, if Neil Gorsuch is confirmed by the Senate, will enjoy a conservative Supreme Court majority. The GOP has absolute control — the governor and legislature — in 24 states. For Democrats, that number is seven, with none between the West Coast and the Northeast.

The chair also comes to the job after an election marred by Russian hackers stealing the DNC’s internal communications.

New Hampshire Chairman Ray Buckley puts it plainly: “Our party has a long way to go.”

WHO ACTUALLY VOTES?

Leading contenders have spent hundreds of thousands of dollars traveling and wooing the 442 eligible voters who make up the Democratic National Committee (a handful of the 447 DNC seats are vacant).

Winning requires a majority of those voting Saturday, with as many rounds as it takes to identify the winner. Perez’s campaign insists he’s nearing that threshold, though Ellison disputes that notion. Buttigieg acknowledges that his strategy is to hope neither Perez nor Ellison can reach a majority after several ballots, leading DNC members to turn to him as an alternative.

IS THIS CLINTON VS. SANDERS II?

There are undertones of the 2016 presidential primary, but Ellison, Perez and their backers say framing the race that way is wrong.

An unapologetic liberal, Ellison has highlighted his endorsement from Vermont Sen. Bernie Sanders, the independent whose strong grass-roots support nearly upended the Democratic primary.

Perez got in the race at the urging of then-President Barack Obama and Hillary Clinton allies, and he has the endorsement of former Vice President Joe Biden. That makes him the perceived establishment candidate at a time many rank-and-file Democrats want a house-cleaning at the party’s top echelon.

But Texas Democratic Chairman Gilberto Hinojosa explains, “I come from the left, left, left wing of the Democratic Party, and I fully support Tom Perez.” Noting Perez’s career work for organized labor and as a civil rights attorney, Hinojosa adds, “Tom is absolutely a progressive.”

Wisconsin Chairwoman Martha Laning says her delegation includes “many strong Hillary Clinton supporters backing Keith Ellison.” Laning backs Ellison not because he is a “progressive champion” but because of his plans for rebuilding state and local parties.

It’s also worth noting that Ellison has an endorsement from Schumer, the Senate leader who’s not exactly a hero in liberal Democratic circles.

“This isn’t about Hillary Clinton or Bernie Sanders,” said Laning. “You have to look at whether somebody is going to be more about just supporting the (presidential) nominee or truly about a 50-state strategy.”

Brazile, meanwhile, scoffed at the idea of a 2016 redux. “I was for her. I was for him,” she quipped. “Hell, no! We are for them, the people of America!”

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