Former US Secretary of State Hillary Clinton, considered as the strongest among the Democrat presidential candidates, seemed to be losing steam six weeks after launching her campaign for the 2016 US presidential election.

A new Quinnipiac University poll revealed that the wife of former President Bill Clinton appeared to be losing public support as her numbers across nearly every key indicators—from trustworthiness to caring—continued falling.

The new survey showed Clinton registering a minus 11 favourability rating in the poll with only 40 percent of voters viewing her positively and 51 percent negatively. More than 50 percent of independents view her negatively.

"(Republican presidential candidate and real estate mogul Donald) Trump and Clinton have the worst scores among top candidates on honesty and caring," the university poll said in a statement posted on its official website on Thursday.

"Clinton is not honest and trustworthy, voters say 57-37 percent, and doesn't care about their needs and problems, voters say 52-45 percent," it added.

Tim Malloy, assistant director of the Quinnipiac University Poll, questioned Clinton's capability to dominate and remain on top of the race for the general elections in November 2016 with unflattering trustworthy rating.

The poll was conducted amid reports of the existence of a classified information on Clinton's private email server and while she has been investing heavily on a campaign designed to attract Americans who felt being left behind in economic recovery.

But pundits said her weak numbers at the polls have yet to affect the perception among 58 percent of Americans who still view Clinton as a strong leader.

Clinton's position as a front-runner for the Democratic nomination remains solid with 55 percent of Democrats supporting her, which has been roughly unchanged from a year ago.

If the election were held today, Clinton would beat Trump, the current frontrunner of the Republican presidential nomination race, the Quinnipiac University poll showed. However, she could find herself in a tie with either former Florida Gov. Jeb Bush or Wisconsin Gov. Scott Walker.

The Quinnipiac University surveyed 1,644 registered voters—made up of 710 Republicans and 681 Democrats—over phone interviews nationwide from July 23 to 28 with a margin of error of +/- 2.4 percentage points.

The results of the new poll came a day after Clinton criticised abortion-rights group Planned Parenthood, admitting she was disturbed after watching undercover videos of the group officials discussing the sale of foetal tissue.

"I have seen pictures from them and obviously find them disturbing," Clinton told the New Hampshire Union Leader.

Nevertheless, Clinton defended the group, saying the videos cannot disregard the facts that Planned Parenthood had indeed done "a really good work for women: cancer screenings, family planning, all kinds of health services."