Axios

With President Trump's base support beginning to erode and a Republican-held Congress failing to achieve any of its chief policy aims, the stage seems set for a Democratic takeover of the legislative branch in 2018. But Democrats are staring down one huge obstacle: the Senate map.

The problem: 25 Senate seats currently held by Democrats or independents caucusing with them are up for election in 2018 — more than half of the Democratic caucus. Even more significantly, 10 of those seats are in states that voted for Trump in 2016. Conversely, just eight Republican seats are up for election with only one in a state that went for Hillary Clinton.