Democratic challenger Jon Ossoff has been declared the winner of his runoff election against former Sen. David Perdue, according to ABC News and NBC News.

With Ossoff's win, the Senate is now split 50-50 between Democrats and Republicans. In the event of a tie, the vote will be broken by the vice president, which will be Kamala Harris after Jan. 20. 

Ossoff declared himself the winner on Tuesday night even though news outlets hadn't yet officially called it. In order to avoid a recount, candidates in Georgia have to win by more than .5 percent, something that was unclear as the mail-in ballots were still being counted. 

But through the night, the vote totals made it clear that Ossoff was the likely winner because the remaining votes were coming from heavily-Democratic areas in Georgia.