The U.S. Capitol Building is visible in the early morning hours of April 2. Andrew Harnik/Getty Images hide caption toggle caption Andrew Harnik/Getty Images Stay up to date with our Politics newsletter, sent weekly . 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.…