The US Senate will remain a Republican-majority chamber, with 34 races mostly ending in the GOP's favor Tuesday. Democrats, however, did gain a seat, leaving them with 48 to the Republicans' 51.

History was made in Nevada, where former state attorney general Catherine Cortez Masto (D) became the first Hispanic woman to win a US Senate seat, with 48.4 percent, compared to Representative Joe Heck's (R) 44 percent, based upon 31.35 percent of precincts reporting, according to Bloomberg.

One US Senate race where the Democrats most highly anticipated a seat pick up was in Wisconsin, but late into Tuesday evening, incumbent Senator Ron Johnson (R) was declared the winner over former Senator Russ Feingold (D), 51.9 percent to 45.2 percent, with 69 percent of precincts reporting, according to the Associated Press.

Other competitive Senate races were in Missouri, New Hampshire, North Carolina and Pennsylvania. Results came in first from North Carolina, where incumbent Senator Richard Burr (R) defeated Deborah Ross (D), 51.6 percent to 44.8 percent, according to AP.

In Missouri, with 90 percent of precincts reporting, incumbent Senator Roy Blunt (R) won with 50.2 percent against the state's Secretary of State Jason Kander (D) 45.3 percent.

In Pennsylvania, with 89 percent of precincts reporting, incumbent Senator Pat Toomey (R) won with 48.9 percent against Katie McGinty (D) with 47.2 percent.

In Indiana's Senate race, Representative Todd Young (R) edged out former Senator Evan Bayh (D), 52.2 to 42.4 percent, according to AP. And in Florida, based on 99 percent of precincts reporting, Senator Marco Rubio (R) won reelection, with 52.1 percent to 44.2 percent against Representative Patrick Murphy (D).

In New Hampshire, with 91 percent of precincts reporting, incumbent Senator Kelly Ayotte (R) led with 48 percent against Governor Maggie Hassan's (D) 47.8 percent.

Louisiana's Senate race featured nearly two-dozen candidates, so it will continue on to a run-off between the top two vote getters, state treasurer John Kennedy (R) with 25 percent and Foster Campbell (D) with 17.5 percent. This seat is expected to go to Kennedy, which would give the GOP 52 Senate seats.