WASHINGTON — In the shadow of the presidential campaign, the parties are also waging a fierce battle over control of the Senate in 2020.
Republicans hold a 53-47 edge, so Democrats need a net gain of four seats to seize the majority — or three if Joe Biden wins the presidency. (When the Senate is split 50-50, the vice president is the tiebreaker.) With Democrats likely to keep their majority in the House, the Senate outcome will determine whether the next president will be dealing with a divided Congress or, as political handicappers increasingly predict, one with Democrats controlling both chambers. That would be a big boon for Biden if he wins or a big headache for President Trump if he gains a second term. Here are some of the key races: