Charles Dharapak/AP Photo

Of all the candidates running for president in 2012, President Barack Obama has received the most negative portrayal in the news media, according to a new study by the Pew Research Center’s Project for Excellence in Journalism.

Researchers found that “negative assessments of Obama have outweighed positive by a ratio of almost four to one” across 11,500 news media outlets they tracked for 23 weeks, between May 2 and October 9. Only 9 percent of news stories and blogs related to Obama over the period were identified as positive, compared with 34 percent negative and 57 percent neutral, or “straight news accounting of events,” the report concluded.

Pew used a “trained” computer algorithm to analyze coverage of political candidates, including the president, in newspapers, cable channels, radio and broadcast networks and thousands of blogs, tagging statements within each as either positive, neutral, or negative based on criteria determined by researchers.

Overall, coverage of Obama was never more than 10 percent positive, the study found.  Moreover, negative coverage of Obama always exceeded positive coverage by at least 20 percentage points. While the study did not examine reasons for the findings, the intense critical spotlight on the presidency and the country’s persistent economic woes that have plagued the administration are likely two factors that influenced results.

Meanwhile, Texas Gov. Rick Perry has received the most coverage and most positive coverage than any other Republican candidate, Pew found.  Thirty-two percent of statements or assertions related to Perry were positive, while just 20 percent were negative. Tea Party-aligned candidates – Perry, Palin, Bachmann and Cain – all received more positive than negative coverage, the study found.

Current GOP frontrunner and former Massachusetts Gov. Mitt Romney has been subjected to less flattering but more split news coverage, with 26 percent of Romney references taking a positive tone and 27 percent taking a negative one.