Democrats’ resounding victories in the New Jersey and Virginia governor’s races got most of the headlines, but the most dramatic results in last month’s elections were downballot. In Virginia, Democratic challengers flipped 13 seats in the Virginia House of Delegates, to secure their largest majority in the chamber in four decades. New Jersey Democrats grew their margin in the assembly by five seats—winning their largest majority since Watergate. Coupled with the party’s string of upset victories and double-digit shifts in special elections last year, the results have some party leaders dreaming big.

How big? A new post-election analysis from the Democratic Legislative Campaign Committee, which supports Democratic candidates in statehouse races, argues that the current electoral climate presents the best chance in years for Democrats to consolidate power in blue states, flip battleground chambers, and loosen Republicans’ grip on power in solidly red states like South Carolina and Missouri.

By the group’s calculations, Democratic candidates over-performed the partisan leaning of their districts this fall by an average of 4.5 points—a shift that would put as many as 651 state legislative seats in play across the country in a midterm election year, and position the party for a bit of long-awaited payback.