Likely Democratic presidential candidate Hillary Clinton has slipped dramatically in match-ups against potential Republican rivals among Colorado voters in a swing-state poll released Thursday morning by Quinnipiac University. Clinton is in a statistical tie with all seven of the GOP candidates polled, marking a drop from leads she held in a previous poll released in mid-February.

Pollsters attribute Clinton’s decline to questions voters have over the private email account she maintained as secretary of state, reporting that the scandal has driven up negative sentiments against her and boosted concerns about her honesty and trustworthiness.

Kentucky Sen. Rand Paul, who officially launched his campaign this week, performs best among the Republican field against Clinton in Colorado, leading Clinton 44 percent to 41 percent. Paul also has the highest favorability rating of the Republican contenders, although a full third of Colorado voters say they haven’t heard enough about him to make up their minds. (Paul’s lead, like the differences between support for Clinton and all the Republicans polled, is within the survey’s margin of error.)

Quinnipiac has been conducting its Swing State Poll since mid-2013, matching Clinton against possible GOP rivals as they emerge. The pollster also reported results on Thursday from polls in Iowa and Virginia. Clinton performed similarly against Republicans in Iowa but polled substantially better in Virginia than she did in Colorado. The Colorado poll had a margin of error of plus-or-minus 3.3 percent.

“In all three of these states, more, and in Colorado many more, registered voters say she is not honest and trustworthy,” said Peter A. Brown, assistant director of the Quinnipiac University Poll, in a release. “Voters do think she is a strong leader — a key metric — but unless she can change the honesty perception, running as a competent but dishonest candidate has serious potential problems.”

Colorado swung its nine electoral votes to Democrat Barack Obama in the last two presidential elections. The state voted for his Republican predecessor, President George W. Bush, in the two previous elections. Politicos predict that Colorado will again be one of just a handful of competitive battleground states in the 2016 election.

In addition to Paul, Texas Sen. Ted Cruz is the only other Republican candidate to have officially announced a campaign, although several other candidates are moving toward making it official in coming months. The other possible candidates polled by Quinnipiac were former Florida Gov. Jeb Bush, Wisconsin Gov. Scott Walker, Florida Sen. Marco Rubio, former Arkansas Gov. Mike Huckabee and New Jersey Gov. Chris Christie.

Clinton runs behind three of the Republicans polled: Paul has 44 percent to her 41 percent; Walker leads Clinton 42 percent to 41 percent; Rubio leads 41 percent to 40 percent. She’s tied with Huckabee at 41 percent apiece. Clinton leads Cruz 42 percent to 41 percent, runs ahead of Bush 41 percent to 38 percent and scores 41 percent to 39 percent against Christie.

In February, Clinton had leads outside the margin of error in the Quinnipiac poll over Bush, Huckabee and Christie. She led Paul, Walker and Cruz within the margin of error.

Colorado voters view Clinton less favorably since February, according to the poll. In the most recent survey, 41 percent reported favorable impressions of the Democrat and 51 percent said they viewed her unfavorably. That’s a shift from a 46 percent favorable, 47 percent unfavorable two months ago.

Paul, Walker and Rubio are the three Republicans with net-favorable ratings from Colorado voters, though all three have high percentages of voters who don’t hold an opinion. Christie has the highest negative rating, with 48 percent saying they hold an unfavorable opinion of him compared with just 22 percent who are favorably inclined. Bush is a close second in the negative sweepstakes, with 44 percent viewing him unfavorably and 29 percent reporting positive feelings toward him.

By a margin of 56 percent to 38 percent Colorado voters say Clinton isn’t honest and trustworthy. When it comes to deciding who gets their vote, 51 percent of Colorado voters say the email controversy is “very important” or “somewhat important,” while 49 percent say it’s “not so important” or “not important at all.” Just 34 percent of voters say she’s answered questions about the emails satisfactorily, while 57 percent say they still have questions. At this point, 42 percent of voters say the way she handled her emails make them less likely to vote for her, while 55 percent say they don’t care.

“Hillary Clinton still has a mountain or two to climb to win the hearts of Coloradans who don’t trust her,” said Tim Malloy, assistant director of the Quinnipiac University Poll, in a statement. “The email controversy is opening doors to candidates who had little traction as Hillary Clinton gets bad numbers on trust and honesty.”

Other Republicans making noise about potential runs include former Pennsylvania Sen. Rick Santorum, who won Colorado’s caucus vote in 2012; South Carolina Sen. Lindsey Graham; former Texas Gov. Rick Perry; former Hewlett Packard CEO Carly Fiorina; and retired neurosurgeon Ben Carson. Democrats who are considering runs include Vice President Joe Biden, former Maryland Gov. Martin O’Malley and former Virginia Sen. Jim Webb.

The Quinnipiac Swing State Poll surveyed 894 self-identified registered voters in Colorado from March 29 to April 7. The poll was conducted by interviewers speaking both English and Spanish who reached land lines and cell phones. The breakdown by reported party identification was 26 percent Republican, 28 percent Democrat, 37 percent unaffiliated and 9 percent who claimed another party or didn’t answer.

— Ernest@coloradostatesman.com