Arizona Democrat and former astronaut Mark Kelly has been sworn into the Senate.
Kelly defeated Republican Sen. Martha McSally in last month's election. By taking office, Kelly has narrowed GOP control of the Senate to a 52-48 advantage.
That won't do much to weaken Senate Majority Leader Mitch McConnell's control of the chamber. But it does set the stage for the two runoff Senate elections in Georgia in January. If Democrats win both of those races, they will control the 50-50 chamber because Vice President-elect Kamala Harris would cast tie-breaking votes.
