WASHINGTON — Americans are increasingly rejecting the two major political parties, according to new polling. Just under half, 45 percent, of U.S. adults now identify as independents, a new Gallup survey found. That’s a substantial shift from 20 years ago, when closer to one-third of Americans said they didn’t identify with the Democrats or Republicans. This group appears, increasingly, to be driven by their unhappiness with the party in power, according to Gallup's analysis. That's a dynamic that could be good for Democrats in this year’s midterm elections, but doesn’t promise lasting loyalty. Independents have gravitated toward the Democrats over the past year when asked which party they lean toward, Gallup found, but attitudes toward the party haven’t gotten warmer. That suggests that the Democrats' gains are probably more related to independents’ increasingly sour views of President Donald Trump. Younger people, in particular, are rejecting the parties at much higher rates than older generations. More than half of Generation Z and Millennials identify as political indep