Susan Page and Jenny Ung

USA TODAY

WASHINGTON — Americans aren't just for or against presidential candidates this year: Color them scared.

In a national USA TODAY/Suffolk University Poll, likely voters given the choice of four options — enthusiastic, satisfied, dissatisfied or scared — are most inclined to say the prospect of Donald Trump winning the Republican nomination or Hillary Clinton winning the Democratic one would leave them fearful.

The findings underscore an increasingly bitter divide in American politics. Partisans on both sides warn that the leading candidate on the other side would not only pursue unwelcome policies in the White House but would imperil the nation's fundamental values and constitutional principles.

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That strong antipathy, which touches a third of independent-minded voters, will complicate the candidates' task of appealing to swing voters and reaching across party lines in the general election. The poll of 1,000 likely voters, taken Thursday through Monday, has a margin of error of plus or minus 3 percentage points.

"Both Donald Trump and (Texas Sen.) Ted Cruz scare me," Harry Bond, 30, of Raleigh, N.C., who was among those polled, said in a follow-up interview. "We need people who will bring people together rather than further alienate everyone."

"I'm voting for anyone but Hillary," declared Alyssa Van Wagenen, 29, of Meridian, Ind.

But for Trump, 38% of likely voters would be scared if the real-estate mogul won the GOP nomination — including not only 62% of Democrats but also 17% of Republicans. A third of independents, 33%, feel that way.Of the three candidates tested, voters were inclined to have a positive reaction only for Vermont Sen. Bernie Sanders. Thirty-one percent of those surveyed say they would be satisfied if he won the Democratic nomination, a bit more than the 28% who would be scared.

And for Clinton, a former secretary of State, 33% would be scared — including 60% of Republicans and also 8% of Democrats. Just over a third of independents, 35%, agree. Sanders is viewed somewhat more positively by Republicans and independents than Clinton was. However, Democrats are more likely to be scared his nomination: 45% of Republicans, 28% of independents and 12% of Democrats say that would be their reaction.

The poll makes clear the headwinds ahead for Trump and Clinton, if they prevail in the primaries.

For Trump, a majority of likely voters, 56%, have a negative response to his prospective nomination, including 18% who would be dissatisfied. Just under four in 10 have a positive reaction: 15% enthusiastic and 24% satisfied.

Clinton fares only a bit better: 54% have a negative response to her nomination, including 21% who would be dissatisfied. Just over four in 10 have a positive reaction: 16% enthusiastic and 26% satisfied.

The response to Sanders' nomination was an even split: 46% with a positive reaction — including 16% who would be enthusiastic — and 46% a negative one.

USA TODAY's 2016 Presidential Poll Tracker