Weeks before Hillary Clinton officials are due to declare she is running in the 2016 White House race, the first opinion poll shows support for her presidential campaign is softening amid controversy over her use of personal email .
Support for Mrs Clinton's candidacy has dropped about 15 percentage points since mid February among Democrats, with as few as 45pc saying they would support her in the last week, according to a Reuters/Ipsos tracking poll. Support from Democrats likely to vote in the party nominating contests has dropped only slightly less, to a low in the mid-50s over the same period.
Even Democrats who said they were not personally swayed one way or another by the email revelations said that Mrs Clinton could fare worse because of it, if and when she launches her presidential campaign, a separate poll showed.
Democratic strategist Ben LaBolt, a former spokesman for President Barack Obama's 2012 campaign, said that the email controversy has been a "galvanising call for the Clinton campaign-in-waiting to build an organization", by hiring top political communicators who can defend her record.
Mrs Clinton, who ran for the White House in 2008 and lost to Mr Obama, is expected to announce as early as next month that she plans to seek the White House in 2016.
Former congressional and Justice Department spokesman Brian Fallon, White House aide Jennifer Palmieri and Jesse Ferguson, who has handled press for Democratic congressional campaigns, are expected to be among the communications experts joining Mrs Clinton's campaign. All three are highly respected in Democratic political circles.
"Democrats want to see Secretary Clinton work for the nomination, but with the string of appointments her campaign has announced in the early (voting) states despite a weak field of competitors, every indication is that she plans to," Mr LaBolt said.
The online poll of 2,128 adults from March 10 to March 17 revealed that Americans, including two-thirds of Democrats, said they were aware of the controversy surrounding her decision to use her personal email rather than a government account, along with a personal server, when she was the top US diplomat from 2009 to 2013.
More than a third of Democrats and 44pc of political independents agreed that the email issue has hurt the former secretary of state politically.
"I admire the fact that she has been so strong on a lot of different things, she stands up for what she believes in, but I do think the emails will hurt her, unfortunately," said Patricia Peacock (49) of Lewiston, Maine, who took part in the survey.
Mrs Clinton has tried to face down accusations that she used her personal email account to keep her records from public review, which would support an old political narrative that Mrs Clinton and her husband, former President Bill Clinton, are secretive and seek to play by a different set of rules.
Mrs Clinton told a packed room of reporters at the United Nations earlier this month that she used her personal email for official business for the sake of convenience, because it was easier to carry only one device.
While her office said she has since turned over paper copies of more than 30,000 work emails last year at the State Department's request, but did not hand over about 32,000 that were private or personal records.
The cache included 300 emails related to a 2012 attack on a US consulate in Benghazi that led to the death of a US ambassador and three other Americans, which were subsequently handed over to a Republican-led congressional committee investigating the incident.
The panel has subpoenaed Clinton's remaining emails and said they would like her to testify on the matter before April.
About half of the adults surveyed, including 46pc of Democrats, agreed there should be an independent review of all Mrs Clinton's emails to ensure she turned over everything that is work related.
More than half of Americans - and 41pc of Democrats - said they supported the Republican-controlled congressional committee's effort to require Mrs Clinton to testify about the emails, the Reuters/Ipsos poll showed.
About half of Democrats said they thought Clinton was composed during the March 10 press conference, but 14pc found her evasive and 17pc said she avoided answering questions directly.
Survey respondent Tom Trevathan (74), a retired professor from Arkansas, said he was "less than happy" with her performance at the news conference.
"It reminds me of a history she has had not responding thoroughly to inquiries," Prof Trevathan said. "If she would be more open about the situation, and show more leadership in saying what she did and why, I think it would be better."