QuinnipiacA new poll finds Democratic presidential candidate Hillary Clinton is trailing three leading Republican contenders in Iowa and two other key swing states. The Quinnipiac University Poll released this morning found just a third of registered voters in Iowa have a favorable opinion of Clinton, while 56 percent view her negatively.

“Former Secretary of State Hillary Clinton’s support in Iowa and two other important swing states — Virginia and Colorado — has dropped a decent amount,” says Peter Brown, assistant director of the Quinnipiac University Poll.

Clinton’s favorable rating has dropped 12 points since a similar survey in April and Brown says that “has to be worrisome” for Clinton.

“When voters are asked about whether a candidate is honest and trustworthy, whether a candidate understands the problems of average voters, whether the candidate is a strong leader — her numbers have consistently fallen,” Brown says.

Vice President Joe Biden, who is a considering a run for the White House in 2016, is viewed by Iowa voters as more honest and caring than Clinton. In head-to-head match-ups, Clinton trails both Wisconsin Governor Scott Walker and Florida Senator Marco Rubio by eight points and she lags behind former Florida Governor Jeb Bush by six points.

“That’s an improvement for the Republicans and a drop off for Mrs. Clinton compared to the last time Quinnipiac polled back in April,” Brown says.

The poll found Bernie Sanders, the independent senator from Vermont who is challenging Clinton for the Democratic Party’s presidential nomination, does as well as Clinton in the same head-to-head match-ups with Walker, Rubio and Bush.

“Sanders does better than some might have expected,” Brown says.

The Quinnipiac Poll also asked voters how they viewed each of the 17 Republican presidential candidates and Brown says for every voter who had a positive view of Donald Trump, there were two who have a negative impression of Trump.

“Mr. Trump gets by far the highest negative rating,” Brown says. “…It’s an indication that perhaps Mr. Trump will have trouble growing his coalition because so many people says that they see him unfavorably.”

The poll was conducted July 9-20 and the Iowa results have a margin of error of 2.8 percent.