The US Democratic Party retained control of the Senate. This happened as a result of the victory in the state of Nevada of the incumbent senator Catherine Cortez-Masto.
She overtook her rival, Republican Adam Laxalt. According to Politico , after counting 98% of the ballots, Cortes-Masto had 48.8% of the vote, Laxalt had 48.1%. Thus, the Democrats are guaranteed to have 50 out of 100 seats in the Senate.
Democrats don't have to win a runoff victory in Georgia in December to win a majority of seats. In the event of a draw, they are guaranteed the vote of Democrat Kamala Harris, who is the chairwoman of the Senate.
Previously, the Republicans won control of the lower house of Representatives by a narrow majority. CNN writes that even that would allow them to shape the remainder of Biden's term, blocking priorities like abortion rights and launching investigations into his administration and family.