More than other voters, they tend to be young, and Black or Hispanic. They get more news from social media than most voters do. They worry about their economic security.

And they use phrases like “lesser of two evils” to describe the choice between former President Donald J. Trump and Vice President Kamala Harris.

These are the undecided, the unhappily committed and the uncertain voters who could make the difference in this tight presidential election.

Although most Americans are firmly in one camp or another, about 18 percent of likely voters nationwide have not definitively made up their minds, according to the latest New York Times, Philadelphia Inquirer and Siena College poll.

A sliver of them are truly undecided; they do not know how they will actually vote. Others say they have made up their minds, but they acknowledge that their preference may not stick once their ballots are in hand.

The uncertainty and detachment of these voters can confound the campaigns. Some will change their minds, perhaps more than once, before Election Day. Others may not vote at all. Their indecision has drawn some scorn from partisans on either side.