WASHINGTON—Republicans seized control of the Senate after picking up seats in West Virginia and Ohio and beating back challenges in Florida, Nebraska and Texas.Republicans had been favored to win a majority in the chamber;

Republicans have successfully retaken control of the Senate after flipping seats in several key states on Tuesday, including Ohio and West Virginia. Heading into Election Day, the GOP was widely favored to wrest back control of the upper chamber from Democrats,

The G.O.P. governor easily won the seat being vacated by Senator Joe Manchin III, an independent who caucused with Democrats, giving Republicans an expected win as they push to take the Senate.