As far as Slate is concerned, there are two U.S. House races in Colorado worth watching tonight. One is in the 7th Congressional District, where incumbent Ed Perlmutter is fending off Republican challenger Ryan Frazier, an Aurora city councilman. The other, higher-stakes race is in the 4th Congressional District, where Betsy Markey sailed to victory after a famously bitter challenge with Republican Representative Marilyn Musgrave just two years ago. And although national Democrats have in the past abandoned the 4th District, which prior to Markey had been solidly Republican, they apparently now see it as worth fighting for to the end.

The Democratic Congressional Campaign Committee seems to believe Markey still has a shot at keeping the district out of the hands of Cory Gardner, her Republican challenger from rural Yuma County, as well as the trailing American Constitution Party candidate Doug Aden and independent Ken Waszkiewicz.

The committee is also going on the offensive for Perlmutter and many other candidates around the nation in the hopes of preventing—or at least minimizing—the conservative avalanche anticipated in the U.S. House after ballots are counted tonight, writes The Wall Street Journal. Perlmutter is facing a tight race in his nearly evenly split Democratic/Republican district, as The Colorado Independent reports: “Perlmutter holds a seat that even if he wins re-election again may always be coveted by Republicans.”