President-elect Joe Biden has chosen former Senate candidate Jaime Harrison of South Carolina as the next chair of the Democratic National Committee and a host of Biden’s top allies as vice chairs, as he moves to remake the national party infrastructure to better compete with Republicans.

The slate of Biden allies who will take over the upper ranks of the party under Harrison include Atlanta Mayor Keisha Lance Bottoms; Michigan Gov. Gretchen Whitmer; Sen. Tammy Duckworth (Ill.); and Rep. Filemon Vela (Tex.).

Harrison, 44, a former chair of the South Carolina Democratic Party who lost his bid for national chair in 2017, raised more than $130 million in his effort to defeat Sen. Lindsey O. Graham (R) last year, making himself a well-known name among Democrats nationwide. His candidacy for the DNC chairmanship had been promoted by Rep. James E. Clyburn (D-S.C.), a close Biden ally who played an instrumental role for the president-elect during his Democratic primary contest.

“This group of individuals represent the very best of the Democratic Party,” Biden said in a statement Thursday. “We need to elect Democrats across our country and up and down the ballot. To do that is going to take tireless leadership committed to strengthening Democratic infrastructure across our states. . . . I know they will get the job done.”

The proposed party leadership, who are not expected to face an internal challenge, will arrive as the Biden transition effort has begun planning for a renewed focus on party-building at the national level in the coming years. It also comes amid a desire for strengthening the party structure after an election that, while it resulted in Biden’s victory and narrow control of the Senate, saw Democrats lose ground in the House, complicating efforts to push through his agenda.

President Barack Obama had initially housed his own political operation at the committee, a decision many Democrats now blame for allowing a weaker party structure that made it possible for Republicans to catch up and in some cases pull ahead in the race for data and organizing.

“I’m thrilled by this slate of officers, all battle-tested, brilliant leaders that build on our party’s successes, reflect the great diversity of the Party, and will work to expand our successes up and down the ballot,” incoming deputy White House chief of staff Jen O’Malley Dillon, who previously served at the DNC and as manager of Biden’s recent campaign, said in a statement. “These leaders know what we need to do to ensure the party is strong, inclusive, and continues to expand our coalition of support across the states.”

The DNC by tradition does not have competitive internal elections after winning the White House, giving the incoming president the power to shape the party. This year, the election rules for open positions were not announced until this Monday, just three days before candidates were required to submit their names and 10 days before members were set to vote.

The seats up for reelection must be as “equally divided by gender as practical,” under party rules, and are also expected to represent a broad range of racial and ethnic diversity. Bottoms and Harrison are Black, Vela is Hispanic, and Duckworth is Asian. Bottoms, Duckworth and Whitmer were all considered as possible vice-presidential nominees by the Biden team.

Biden has also decided to back another term for Chris Korge, the national finance chair, and Jason Rae, who serves as secretary of the party. Virginia McGregor, the current deputy national finance chair and a native of Biden’s hometown of Scranton, Pa., has been picked by Biden to become the party’s treasurer.

All of Biden’s nominees must now collect signatures by Monday from party membership to appear on the official party ballot by next week. The voting for a replacement, which will be done virtually, will be completed Jan. 21, one day after Biden’s inauguration.

Under Democratic Party rules, the chair wields enormous power, especially when the party has a president in the White House. Harrison, if elected, will have unilateral power over most major decisions and be able to directly appoint members to key governing bodies within the party, such as the Rules and Bylaws Committee, which sets the calendar and rules for the presidential nomination process, and the Budget Committee, which tracks how money is spent.

The Rules and Bylaws Committee is expected to take up the question of whether to change the Democratic nomination process for the 2024 election. While a perennial topic of conversation, the nomination system raised broad concerns within the party after complicated caucuses last year in Iowa and Nevada.

Nevada party leaders have already taken steps to shift to a presidential primary in 2024 — a move that, depending on the timing they sought, could upset New Hampshire, which has long vowed to maintain its place as the first primary contest.

The Rules and Bylaws Committee is required to produce a report about problems with the 2020 nomination — which included a lengthy and flawed count after the Iowa caucuses — by the end of March. Harrison will play a role in shuffling that panel’s membership, probably at the summer meeting of the party later this year.

Another major position up for grabs next week is the president of the party’s Association of State Democratic Committees, who is elected directly by state party chairs instead of all party members.

Ken Martin, the group’s current president and the head of the Minnesota Democratic-Farmer-Labor Party, is seeking reelection to the post, which he is expected to retain.

“It is an exciting time to be a Democrat,” said Martin, who added that the party would need to grapple with downballot losses in the last election. “We need to also reflect on this last election, which in a lot of ways reminds me of that Rolling Stones song ‘You Can’t Always Get What You Want’, but you get what you need.’ ”

He said that conversations about the future of the Democratic nomination process had already begun and that he supports a full discussion within the committee.

“The biggest question is: What does President Biden and Vice President [Kamala D.] Harris think about it, because they are the leaders of the Democratic Party,” Martin said.