Poll: Chris Christie, Hillary Clinton may have credibility issues

For two top presidential prospects in 2016, credibility could be a problem on the campaign trail.

According to a new Bloomberg News poll, 63 percent of Americans say they don't believe New Jersey Gov. Chris Christie's claim that he knew nothing about the George Washington Bridge controversy, in which his top aides ordered the closure of certain access lanes on the bridge in an apparent act of political retribution.

That number includes 43 percent of Republicans who don't believe the brash Republican governor. Sixty-three percent of independents don't believe him, and a whopping 79 percent of Democrats.

Former Secretary of State Hillary Clinton fares only slightly better when it comes to whether or not she knew about a request for additional security at the U.S. diplomatic compound in Benghazi, Libya, ahead of a 2012 attack. Clinton has denied knowing about the request, but more than half of Americans don't believe that.

That number includes a quarter of Democrats, 57 percent of independents and a full 77 percent of Republicans.

Both politicians have seen their favorability ratings take a toll in recent months. Clinton is down to 56 percent after a high of 70 percent in December 2012, just before she left office. A separate Wall Street Journal/NBC News poll conducted last week revealed a similar 14-point drop among people who had a very or somewhat positive view of her, falling from 58 percent in December 2012 to 44 percent in March, and her negative rating was up from 38 percent in December 2012 to 34 percent now.

According to the Bloomberg News poll, Christie's popularity is down to 32 percent from 50 percent in June, before the bridge scandal unfolded.

Clinton would still beat Christie 52 percent to 39 percent in hypothetical head-to head presidential matchup, with independents favoring her by a razor-thin margin of 45-43 percent.