The 2016 presidential candidates are still facing a major hurdle: Americans just don't seem to like them very much, according to new polling. 

A new Associated Press – GfK poll shows seven in 10 people, including close to half of Republican voters, have an unfavorable view of GOP front-runner Donald Trump. The poll saw a consistent disdain for Trump across all demographics: young and old; conservatives, moderates and liberals; and whites, Hispanics and blacks. Despite Trump's attempts to portray himself as a unifier, 63 percent of those surveyed said they would not vote for Trump under any circumstances.

The poll also underscores the trouble he may still face in the Republican race, which may be headed to a contested convention where party insiders would have their say about who represents the GOP in the fall campaign.

"He's at risk of having the nomination denied to him because grassroots party activists fear he's so widely disliked that he can't possibly win," said Ari Fleischer, former press secretary to President George W. Bush. 

Trump's not the only one with a popularity problem. 

Trump’s main rival, Texas Sen. Ted Cruz, also is viewed unfavorably by 59 percent of those surveyed. Fifty-five percent said that would definitely not vote for him.

On the Democratic side, former Secretary of State Hillary Clinton also received a high unfavorable rating, with 55 percent saying they view her negatively. Almost 5 in 10 people stated they would not vote for Clinton no matter who the other presidential nominees are.

The Associated Press-GfK Poll was conducted March 31-April 4 by GfK Public Affairs & Corporate Communications. The poll is based on a sample of 1,076 adults, with a margin of error of 3.3 percentage points. 

FoxNews.com’s Danny Jativa and The Associated Press contributed to this report.