So much for a post-racial America.

A slight majority of all Americans show some prejudice toward blacks, whether the realize it or not, according to an Associated Press poll released on Saturday.

In the survey, 56 percent of Americans showed some anti-black feelings, whether implicitly or explicitly. That percentage has actually risen in the four years since President Obama took office—up from 49 percent in 2008—indicating that, if anything, anti-black attitudes have become more prevalent since that landmark election.

That finding is based on poll questions that both directly asked respondents questions about their feelings toward particular races, as well as more subtle questions that gauged racial attitudes without mentioning the subject. Yet on the questions that explicitly gauged overt racism, a slim 51 percent majority of Americans still showed anti-black bias, versus 48 percent who did not.

Republicans were far more likely than Democrats to show some sign of anti-black bias. Seventy-nine percent of Republicans exhibited an explicit anti-black attitude on the more direct questions, versus thirty-two percent of Democrats who did the same.

That finding came one day after Colin Powell's former chief of staff said his Republican party was "full of racists."

The survey also found that not only had the nation inched deeper into anti-black sentiment, but that other races are now subject to more negative perceptions as well. In 2011, an AP survey detected anti-Hispanic responses from 51 percent of Americans; that figure rose to 57 percent in the latest poll.

The findings could pose some trouble for Obama's reelection effort. Pollsters estimated that the president could lose two percentage points off the national vote as a result of the worsened racial attitudes.

The AP survey was conducted onnline between August 30 and September 1, and has a margin of error of four percentage points. Though online surveys are typically regarded as less accurate than live-call polls, the pollsters said such a format was preferable as people are less willing to divulge their true feelings on such controversial issues when speaking to a real person.