Democrats have momentum ahead of the midterms thanks to an unpopular president, the historic slouch among the party in power, and a horde of retiring Republicans.

The one thing they don’t have? A lock on the math.

New analysis from the Center for Politics at the University of Virginia demonstrates that Democrats can’t win a majority simply by carrying the congressional districts won by Hillary Clinton in 2016. To take back control of the House, they will need to win about as many seats in districts Clinton carried as they will in districts Donald Trump carried. Winning will require more than #Resistance.

To retake the gavel and retire Speaker Paul Ryan, Nancy Pelosi and company need to win 25 seats.

Some will be easy, like Arizona's 2nd Congressional District and California's 49th District, which are open and deep blue. Others will be manageable like Pennsylvania's 7th District, which will soon be vacated by disgraced Republican Rep. Pat Meehan. And a couple will be a genuine challenge, like Kansas' 3rd District, which is held by Republican Rep. Kevin Yoder.

Kyle Kondik provided a paint by district outline over at the Center for Politics blog. If Democrats follow his instructions, their majority will be a fresco of blue, purple, and deep red districts.

This is possible, but also problematic because a victory will require moderation. After the State of the Union, it isn’t clear Democrats can do that. While Rep. Joe P. Kennedy III gave a passionate rebuttal that stirred the hearts of coastal liberals, it probably didn’t resonate in middle America. Something needs to change.

Democrats won’t win by emphasizing transgender bathrooms over economic growth. Democrats won’t win by letting it look like they value the children of illegal immigrants over the children of citizens. And Democrats won’t win by accusing a president, who resembles much of the nation, of racism, misogyny, and xenophobia. In short, Democrats can’t #Resist their way to a majority.