But polls over the past year almost invariably have found Clinton improving—often substantially—over President Obama’s lackluster 2012 performance among white-collar white women.

Those college-educated white women have been the fastest-growing part of the white electorate in recent years. If Clinton as a nominee could cement the gains she’s shown among those women in most national and state polls over the past year, she would present Republicans with a formidable demographic challenge, even without improving among any other white voters. Her greatest potential strength, in other words, may be hiding in plain sight: her potential connection to the white-collar white women who most resemble her.

All polls of the 2016 race at this point are recording only distant impressions long before most voters have seriously focused on their choices. The actual campaign, and events yet to occur, will inevitably scramble the equation.

Yet, especially with a candidate as familiar as Clinton, these early soundings can be viewed as a kind of rebuttable presumption: They sketch the coalition that may naturally gravitate to her unless opponents present them with a case not to.