The last few weeks of public polling have offered contradictory and surprising results, like surveys showing the Democratic Senate candidate in Colorado either up by six percentage points or down by eight. Nonetheless, the polls have clarified the fight for the Senate. States like North Carolina and Michigan have moved toward the Democrats, while Arkansas and Louisiana have drifted toward the Republican column. The result is that the list of battleground states has shrunk, with perhaps only Alaska, Iowa and Kansas remaining as true tossups.

Yet even though the overall picture is sharper, it now centers on the two most mysterious contests of the year.

If all of the candidates currently leading in the polls go on to win, which is not at all assured with so many close races and still 45 days to go, then the party that wins two from the list of Iowa, Alaska and Kansas will win the Senate. But Alaska and Kansas pose unusual challenges for election analysts and forecasters. It’s possible that one party has a clear advantage in the fight for the Senate, and that we just don’t know it yet.

The race in Kansas is unusual: It’s barely underway, and it’s not even clear which candidates will appear on the ballot. The Democratic candidate Chad Taylor withdrew from the race on Sept. 3, setting up a potential one-on-one contest between Greg Orman, an independent, and Pat Roberts, the embattled Republican incumbent.