By Larry Kane
PHILADELPHIA (CBS) -- A new presidential poll released today, covering voters in so-called "swing" states, must be raising a red flag for prospective Democratic candidate Hillary Clinton.
Since 1960, no one has won the presidency without taking two of three swing states: Pennsylvania, Florida, and Ohio. According to the latest Quinnipiac University poll, Clinton has a lot of work to do to shore up support in those "must-win" states.
In Pennsylvania, the poll shows likely Republican candidate Rand Paul with 45 percent support among voters, and Clinton at 44 percent.
In Florida, Jeb Bush gets 45 percent to Clinton's 42 percent. And in Ohio, Rand Paul trails Clinton by just five percentage points.
The good news for Clinton is that she still leads all the other Republican candidates -- announced and unannounced -- in those states, including Chris Christie (44-39 percent, but lower than the 51-33 spread she enjoyed in February).
Clinton's e-mail controversy has taken a toll, and there are undoubtedly further challenges ahead for her campaign.
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