WASHINGTON — Sen­a­tors chose par­ty lead­ers Tues­day with few changes at the top, but it’s unclear who will be the major­i­ty leader in the new Con­gress with no par­ty hav­ing secured con­trol of the Sen­ate until a Jan­u­ary runoff elec­tion in Georgia.

Sen. Mitch McConnell, R‑Ky., won anoth­er term as Repub­li­can leader, his office said, cement­ing his role as the longest-serv­ing GOP leader in U.S. his­to­ry. Sen. Chuck Schumer, D‑N.Y. won his party’s sup­port to stay on lead­ing the Democ­rats, accord­ing to a Demo­c­rat grant­ed anonymi­ty to dis­cuss the closed-door balloting.

None of the lead­ers were being chal­lenged in Tuesday’s pri­vate par­ty elec­tions, with their entire lead­er­ship teams set to be reinstated.

But it’s still to be deter­mined whether McConnell will retain his role as major­i­ty leader or cede it to Schumer as the final races for the U.S. Sen­ate play out.

Last week’s elec­tions left the cham­ber split, 48–48, head­ing into the new Con­gress next year. Repub­li­cans brushed back Demo­c­ra­t­ic chal­lengers in sev­er­al states, but failed to lock down the seats need­ed to retain their majority.

Races for two seats in Geor­gia head­ing to a Jan. 5 runoff are swift­ly becom­ing a show­down over con­trol of the cham­ber. The state is close­ly divid­ed, with Democ­rats mak­ing gains on Repub­li­cans, fueled by a surge of new vot­ers. But no Demo­c­rat has been elect­ed sen­a­tor in some 20 years.

Two oth­er seats in North Car­oli­na and Alas­ka remain too ear­ly to call. In North Car­oli­na, Sen. Thom Tillis is try­ing to fend off Demo­c­ra­t­ic chal­lenger Cal Cun­ning­ham in a tight race. Alas­ka GOP Sen. Dan Sul­li­van is favored for anoth­er term against Al Gross, an inde­pen­dent run­ning as a Democrat.

Even if Repub­li­cans secure the final two races where bal­lots are still being count­ed in North Car­oli­na and Alas­ka, they would still fall short of the 51 seats needed.

The math has become more chal­leng­ing for McConnell because the vice pres­i­dent of the par­ty hold­ing the White House casts the tie-break­ing vote in the Sen­ate. Next year that would be Vice Pres­i­dent-elect Kamala Har­ris. That means 50 seats for Democ­rats would result in con­trol over the cham­ber. But Repub­li­cans would need 51 seats to cement their hold on power.

The stakes are high for all sides, with strate­gists expect­ing an eye-pop­ping $500 mil­lion could be spent on the Geor­gia runoff elec­tions in the weeks ahead.

GOP Sen. Kel­ly Loef­fler will face Rafael Warnock, a Black pas­tor from the church where Rev. Mar­tin Luther King, Jr. preached. And Repub­li­can Sen. David Per­due, a top Trump ally, will face Demo­c­ra­t­ic chal­lenger Jon Ossoff.

A Demo­c­ra­t­ic major­i­ty in the Sen­ate, the par­ty that also con­trols the House would give the par­ty a firm grasp on pow­er in Wash­ing­ton. Biden would have lat­i­tude over nom­i­nees, includ­ing for his Cab­i­net, and a chance to push major por­tions of his leg­isla­tive agen­da through Con­gress. If Democ­rats fall short, McConnell could wield the pow­er to check Biden’s ambitions.

The Demo­c­ra­t­ic lead­er­ship team includes Sen. Dick Durbin, D‑Ill., as whip; Sen. Pat­ty Mur­ray, D‑Wash., assis­tant leader, and sev­er­al oth­ers, includ­ing Sen. Eliz­a­beth War­ren, D‑Mass., Sen. Amy Klobuchar, D‑Minn., Sen. Bernie Sanders, I‑Vt., keep­ing lead­er­ship roles. Democ­rats added Sen. Cory Book­er, D‑N.J., and Sen. Cather­ine Cortez-Mas­to, D‑Nev., to the lead­er­ship team.

The Repub­li­can lead­er­ship team is set to include Sen. John Thune, R‑S.D., as whip; with Sen. John Bar­ras­so, R‑Wyo., and oth­ers hold­ing oth­er lead­er­ship roles.