Republican Donald Trump has said he intends to force Mexico to pay for a wall that would keep immigrants out of the United States.
He has also vowed to deport 11 million illegal immigrants.
Democrat Hillary Clinton has promised to limit secret money in politics and rein in Wall Street, the pollsters said.
Quinnipiac’s survey found that only 24 percent of voters believe Trump, if elected, would be able to build a wall and have Mexico pay for it, while 39 percent say he will try and fail.
Twenty-nine percent said he won't even try.
Meanwhile, only 19 percent of those surveyed said the billionaire businessman would be able to deport millions of immigrants.
Forty-five percent said he would try and fail, and 29 percent said he wouldn’t even try.
Trump gets his best score on his promise to ban non-citizen Muslims from entering the U.S., but only 29 percent say he will succeed, the poll found.
Forty-two percent said his efforts will flop; 21 percent say he won't try.
Sixty-three percent of those polled said Clinton would not even try to remove secret money from politics, but 9 percent say she would succeed, and 18 percent say she would fail.
The former secretary of state and first lady also would not try to curb the power of Wall Street, 56 percent said.
Fifteen percent say she would succeed and 21 percent say she would fail.
"No matter which candidate you pick, you can cut the cynicism with a knife," said Tim Malloy, the poll’s assistant director.
"There are grand promises that stoke enthusiasm at rallies, and then there is reality. Voters say Trump would try and likely fail, while Clinton would not even try," Malloy added.
Quinnipiac University surveyed 1,561 registered voters nationwide from May 24 to May 30. The poll has a margin of error of 2.5 percentage points.
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