LAS VEGAS — For nearly two decades, Nevada was one of the most promising opportunities for Democrats on the battleground map — an epicenter of labor power with a youthful, highly diverse population that held many of the elements of a winning Democratic coalition.

But at a time of deep frustration about housing costs, inflation and gas prices, recent polls suggest that Nevada could be slipping from President Biden’s grasp — highlighting his broader struggles to win over younger voters, Hispanics and Americans without a college degree.