U.S. voters began to cast their ballot in the midterm elections as the first polling stations opened Tuesday morning.

At a polling station in Arlington, Virginia, dozens of voters weathered the cold to line up before the doors opened.

The elections will determine which candidates fill 35 Senate seats and all 435 of the House seats in the next Congress, and likely draw the trajectory of U.S. politics for the next two years.

The Republican Party now holds a majority in both chambers of Congress. Most polls projected the Democratic Party to take the House while the Republicans keep control of the Senate, but an abundance of neck and neck races make the final result difficult to predict.

If the Republican Party manages to hold on to the majority in both chambers, it will bolster the current administration's legislative agenda. If the Democratic Party wins a majority in either the House or the Senate, it can greatly undermine the current administration's policy efforts in the next two years.