U.S. President Donald Trump's approval rating — 37 percent according to the most recent Gallup poll —is shockingly low for an office that should be enjoying its political honeymoon and advancing its signature legislative accomplishments. Instead, he is watching any possible accomplishments collapse on the Senate floor — if they even make it that far — and new revelations of his campaign's collusion with the Russian goernment are revealed almost daily. And yet he remains politically viable and will probably continue to be.

For that to change, Democrats would need to capitalize on his low approval rating in order to make gains of their own, and it's not clear if they can do that. Their 2016 strategy was based almost exclusively on the assumption that Hillary Clinton could take advantage of his unpopularity, but that overestimated their ability to keep intact the coalition that twice elected Barack Obama. The trick will be to win back Obama voters who defected to Trump while keeping the base engaged and fired up. In other words, Democrats need to convince the ideologically-driven Bernie Sanders wing of the party to share a tent with voters who were willing to give a racist and nationalist the benefit of the doubt. Giving those sets common cause will be extremely difficult.

Their first test will be the 2018 midterm elections. Historically, the president's party always loses seats in the first set of midterms, but Democrats will need to defend 25 seats in the Senate — more than half of their delegation — and 10 of those are in states that voted for Trump.