Though the U.S. code allows Congress to object to the electoral vote, in 2020 Democrats have the upper hand to reject any move to nullify the results.
The procedure laid out by the U.S. code gives Congress the final say in the elections. Both the House and Senate will meet to formally tabulate the electoral votes and raise any final concerns about the results. The objection to the electoral votes of any individual state must be made by at least one Senator and one Representative, but with certain constraints. It must be presented in writing by at least one member of each Senate and the House. If the objection is valid, both the houses will debate it separately and decide whether it can be entertained. If there’s a split decision, meaning the House voted one way and the Senate voted the other, the objection fails, and votes are counted as originally cast. In short, the objection to a state’s electoral vote must be approved by both the houses for the vote to be excluded.
Given that Democrats have the upper hand in the House of Representatives, it is unlikely that the Republicans would have the votes to disqualify a state. Further, none of the Republicans has come forward and said that he/she would raise objections during the joint session.