The race is on for House Democrats in Congress — and not just for who gets to hold the gavel.

Everyone will be paying the most attention the contest for House Speaker (House Minority Leader Nancy Pelosi is currently the only candidate, but a small contingent of Democrats is determined to vote against her). But the House leadership hierarchy is much more than just one position.

Democrats need to fill a number of spots that will determine who will shape the party’s agenda and strategize on how best to hang on to their majority in 2020.

The biggest disagreement playing out in these elections will be over seniority.

The same trio has led House Democrats for more than a decade — Pelosi, Steny Hoyer of Maryland, and Jim Clyburn of South Carolina are all running for the three top slots again. There’s been a small but growing contingent of Democrats in the House caucus who want new blood at the top, but there’s no one yet willing to challenge Pelosi outright.

As a contentious leadership battle gets underway here’s your guide to understanding the players in the Democratic leadership races, and why they matter.

House Speaker

Who is running: Nancy Pelosi, the current House minority leader, who was House speaker from 2007 to 2011.

What the job is: House speaker is an all-important and all-consuming job. The speaker is the leader of the House caucus office has a large part in deciding what bills can actually make it to the floor, giving them huge power to shape the party’s legislative agenda. As the person in charge, they are also the main face of the caucus.

They have to get the various parts of the caucus to agree on bills, so the job is all about hammering out compromises on bills to get to 218 votes — the magic number to pass a bill on the House floor. To underscore the importance of the job, the House speaker is second in line to succeed the president, after the vice-president.

The larger picture: Pelosi is arguing her past experience as speaker working with a Republican president (George W. Bush) makes her the perfect person to lead Democrats under Trump. Indeed, she is one of the most accomplished speakers in history. But her argument about experience could also be her biggest weakness as a small but growing number of naysayers and new incumbents want a new face of House Democrats. No one has come forward to challenge her; Rep. Marcia Fudge (D-OH) was mulling a bid but announced Tuesday night she will not pursue it and back Pelosi. This decision came after Pelosi named Fudge the chair of the newly reinstated House Administration Subcommittee on Elections.

House Majority Leader

Who is running: Current House Minority Whip Steny Hoyer (MD), who also served as House majority leader when the Democrats were in power from 2007 to 2011.

What the job is: The majority leader has a big hand in scheduling and determining when bills get to the House floor. They also work with committee chairs to bring certain bills out of committee and to the floor.

The larger picture: Just as Pelosi has long been the No. 1 House Democrat, Hoyer has been the No. 2. He’s vying to return to his old job when Democrats were in power, and so far has no challenger. Hoyer faces the same sentiment that the top echelon of leadership needs a change — but he has cultivated loyalty among moderate Democrats especially. 155 Democrats recently signed a “dear colleague” letter in support of him.

House Majority Whip

Who is running: Current Assistant Democratic Leader Jim Clyburn (SC), the third person in the longtime Pelosi-Hoyer-Clyburn leadership trio. Clyburn’s only challenger, Rep. Diana DeGette (D-CO), announced on Monday she’s withdrawing from the whip’s race.

What the job is: The majority whip counts and “whips” votes, convincing a majority of Democrats and Republicans to vote for a bill (remember, 218 is the magic number).

The larger picture: Of the entrenched leadership trio, Clyburn is the only one who is actually facing a challenger for the job of whip. He’s the highest-ranking black House Democrat, which gives him a good layer of protection. The Congressional Black Caucus is a very powerful part of the overall Democratic caucus, and they want representation at the top.

Assistant Democratic Leader

Who is running: Rep. Ben Ray Lujan (NM), the current chair of the Democratic Congressional Campaign Committee. Lujan was initially challenged by Rep. David Cicilline (RI), a co-chair of the Democratic Policy and Communications Committee, but Cicilline announced Wednesday he is running for a newly created DPCC chair position instead.

What the job is: Pelosi actually created the job of assistant democratic leader in 2010 for Clyburn, after he ran against Hoyer for minority whip and lost. It’s now the No. 4 position in the Democratic majority hierarchy (but the third-ranked position when they were in the minority).

The larger picture: Lujan lead the campaign arm of House Democrats during a very successful election year, so he is seen as a formidable candidate to beat for the position (he’s also a close ally of Pelosi’s). Cicilline is a member of the Congressional Progressive Caucus, another large faction of Democrats who would like to see a progressive at the top of leadership — meaning this race could be a showdown.

Democratic Caucus Chair

Who is running: Rep. Barbara Lee (CA), a former chair of the Congressional Progressive Caucus and the Congressional Black Caucus. She’s running against Rep. Hakeem Jeffries (NY), a co-chair of the House Democratic Policy and Communications Committee.

Rep. Linda Sanchez (CA), the current caucus vice chair, recently dropped out of the race for chair after her husband was indicted on federal criminal charges that he used federal money to cover personal expenses.

What the job is: The caucus chair is tasked with overseeing meetings of the entire Democratic caucus. The person supports new members, and helps set the party’s policy agenda.

The larger picture: Jeffries is seen as a rising star in the party, and there’s intense interest in him moving up the ladder quickly from a lot of members in the caucus. Him putting his name in this race is a sign that he’s interested, albeit in a few years. Lee will be a formidable opponent as well; she’s a longtime congresswoman who has connections in the progressive caucus and the CBC.

Democratic Caucus Vice Chair

Who is running: Rep. Katherine Clark (MA), who has worked with the DCCC on candidate recruitment and helping flip red districts in 2018. Rep. Pete Aguilar (CA), a member of the Congressional Hispanic Caucus who authored a bipartisan immigration bill last year, is also running.

What the job is: The vice chair works closely with the chair to oversee the caucus, also helping shape the party’s policy vision.

The larger picture: Clark is beloved by caucus members; she’s a behind-the-scenes Democrat who fellow members say works extremely hard to support new members and candidates. Aguilar is best-known for his bipartisan Hurd-Aguilar bill to protect young, unauthorized immigrants known as DREAMers. (The bill ultimately did not go anywhere under the Republican-controlled Congress.

Chair of the Democratic Congressional Campaign Committee

Who is running: This four-way race is the most competitive leadership race so far; Reps. Cheri Bustos (IL), Denny Heck (WA), Suzan DelBene (WA), and Sean Patrick Maloney (NY) are all running to be the chair of House Democrats campaign arm for the 2020 cycle.

What the job is: The DCCC chair is in charge of getting Democrats reelected, and it’s seen as an important stepping stone to higher positions of leadership if Democrats are successful.

The larger picture: This is going to be a fight over the soul of the Democratic Party; Democrats just won a huge victory in 2018, especially flipping redder suburban districts with moderate candidates. Bustos, another DPCC co-chair who is from a conservative part of Illinois, is making the argument that a middle-America Democrat needs to head up the campaign operation in 2020 to defend those seats. (Bustos also recently dropped out of the assistant leader race to pursue the DCCC chair spot.)

But Heck and DelBene already have DCCC experience, with Heck serving as the committee’s recruitment chair, and DelBene oversaw finance in a record-breaking fundraising year. It could be a contentious race.

Correction: An earlier version of this piece said the House Speaker is third in line to succeed the president. The speaker is second in line, after the vice president.