Democrats now have easier ways to flip the Senate. Here are the races to watch.

Democrats’ chances of flipping the Senate have increased in recent months as President Donald Trump’s unpopularity, as well as frustration over the economy, drives voters away from Republicans.

Democrats were favored to take control of the House, which has a slim Republican majority. In the Senate, the calculation is more daunting: Democrats control 47 seats to 53 for Republicans.