Democratic Senator Catherine Cortez Masto leads a rally ahead of the midterm elections in Henderson, Nevada, US, November 7, 2022. (REUTERS/David Swanson)

With Masto's victory on the heels of Democratic Senator Mark Kelly winning re-election in Arizona late on Friday, Democrats will control at least 50 Senate seats, with Vice President Kamala Harris able to break ties in the 100-member chamber.

If Democratic Senator Raphael Warnock were to win the December 6 Georgia runoff election against Republican challenger Herschel Walker, that would expand Democrats' majority to 51-49.

That would give Democrats an additional edge in passing the few bills that are able to advance with a simple majority of votes, instead of the 60 needed for most legislation.

Republicans are close to win the House of Representatives as it already won 210 seats compared to 200 seats for Democrats. The party that gets 218 seats will gain control of the House.