Washington (CNN) With the midterms now just 29 days away, a new poll of 69 of the most competitive House districts in the country suggests that the Republican majority is in deep, deep peril.

The survey, which was conducted by the Washington Post and the Schar School of Policy and Government at George Mason University, shows that 50% of voters in those 69 seats prefer a generic Democratic candidate for Congress while 46% would rather vote for a Republican.

That 4-point gap might not seem like much. After all, most national polls suggest the Democratic edge is wider! Except ... these same 69 districts favored the generic Republican over the generic Democrat by a 56%-41% margin back in 2016. That's a massive swing -- and it's indicative of just how much Democrats have made inroads in what was Trump country less than two years ago.

Of the 69 battleground seats that the Post polled, 63 are currently held by Republicans. Trump carried 48 of the 69 in 2016. Those two data points speak to just how tilted the playing field in the House truly is: Republicans are defending huge numbers of their own seats -- in areas where Trump did well in 2016 -- while Democrats have almost no problematic incumbents.

What's fueling this building Democratic wave? Women, according to the Post/Schar data. In the 69 battleground seats, women prefer the generic Democratic candidate over the Republican one by a 14-point margin. (Men choose the Republican candidate 51% to 46%).

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