Democrats won control of the U.S. Senate on Tuesday night after NBC News projected Democrat Josh Turek would flip Iowa’s open Senate seat, giving the party the 51 seats needed for a majority.

The Iowa victory capped a wave of Democratic gains that erased the 53-47 Republican advantage that the GOP carried into Election Day.

NBC News’ results showed Democrats with 51 seats after Turek’s projected victory, with Republicans at 39 and several races still unresolved. Democrats had flipped six Republican-held seats, according to NBC’s tally.

Turek, an Iowa state representative and Paralympian, defeated Republican U.S. Rep. Ashley Hinson in the race to succeed retiring Republican Sen. Joni Ernst.

At the time NBC projected Turek the winner, he had about 50.9% of the vote compared with 46% for Hinson, with an estimated 89.5% of the vote counted. Libertarian Thomas Laehn had about 3.1%.

Iowa had emerged as one of the most closely watched Senate contests of the election. No Democrat had been elected to the U.S. Senate from Iowa since 2008, and the state had increasingly favored Republicans in federal elections.

Turek and Hinson were competing for the seat held by Ernst, who announced she would not seek a third term.

The change in control means Democrats will take the Senate majority when the new Congress convenes in January, giving the party control of committees and the Senate floor agenda.