The U.S. Capitol Building is visible in the early morning hours of April 2. Andrew Harnik/Getty Images hide caption

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Andrew Harnik/Getty Images

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The national political environment is a difficult one for Republicans. President Trump is facing record-low approval ratings, his war in Iran is unpopular, and views of the economy continue to be negative.

With the GOP's razor-thin majority in the House, all of that has made Democrats the odds-on favorites to pick up the lower chamber.

But what about the Senate? That's still an uphill climb for Democrats, given that the path to a majority runs through some pretty Republican-leaning places, like Ohio and Alaska.

Because Trump is in the White House, and a vice president breaks ties in the Senate, Democrats need to pick up a net of four seats to take control. Republicans contend they will hold the Senate, but narrowly. They expect Democrats to pick up anywhere from one to three seats.…