WASHINGTON - The 2012 presidential race feels even more bitter than usual as the US news media has struggled to unpick the slew of negative narratives emanating from the rival camps, a study said Thursday.

The Pew Research Center’s Project for Excellence in Journalism (PEJ) examined what it called the “master narratives” in the media coverage of Democratic incumbent Barack Obama and his Republican challenger Mitt Romney. Those about Obama were 72 per cent negative and those about Romney were 71 per cent negative.

Pew, which has monitored the plot lines of the major US political races since 2000, said only the 2004 contest between George W. Bush and John Kerry had been depicted as negatively. “Only in 2000 did we find a narrative about a single candidate substantially more negative than this year, Vice President (Al) Gore, whose personal narrative was 80 per cent negative,” the study said.

News media, operating in tricky economic times, were having a hard time dissecting this barrage of unflattering portrayals on an ever-growing number of platforms in the most expensive race in US history, the study said. “Journalists themselves now play a smaller role in shaping these media narratives than they once did,” the study said. “More of what the public hears about candidates also now comes from the campaigns themselves and less from journalists acting as independent reporters or interpreters of who the candidates are.”

Tom Rosenstiel, director of the Pew project, said shortcuts in reporting sometimes led journalists to accept wholesale the downbeat portrayals provided by a politician’s opponents.

“The American news media in its coverage of the candidates appears increasingly to be a conduit of partisan rhetoric and less a source than it once was of independent reporting,” he said.

“This may reflect the impact of shrinking newsrooms. But it probably also helps explain why the campaign feels so negative.”

The most prevalent negative media narrative about Obama was that his economic policies had failed, a storyline that accounted for more than a third — 36 per cent — of statements about his character and record.

By comparison, just 16 per cent of media portrayals suggested Obama had helped the economy, the Pew study found.

The report found that the number one narrative about Romney was that he is a “vulture” capitalist — an angle that accounted for some 14 per cent of statements about his character.

The second most prevalent narrative — appearing in about 13 per cent of the coverage about the former Massachusetts governor — was that he is a wealthy elitist who is indifferent to the plight of the less fortunate.

The Pew report examined the most prevalent narratives involving each candidate’s character and record during a 10-week period from May 29 through August 5.

It found that five of the six most prevalent master narratives in the press about Obama’s character and record were negative, as were five of the six most prevalent themes about Romney.

The study analyzed more than 1,772 assessments of the candidates’ character and record found in more than 800 stories from 50 major news outlets.

It was published just ahead of the party nominating conventions, which signal the beginning of the candidates’ hectic final push for the White House and weeks of all-out campaigning across key swing states.

The Republicans hold their nominating convention in Tampa, Florida next week, while Democrats hold theirs the following week in Charlotte, North Carolina.

“As the candidates try to re-introduce themselves to voters, the study shows that the press has delivered these voters a remarkably negative story for both Obama and Romney,” said Pew associate director Mark Jurkowitz.

“The negative theme about Obama’s economic record is winning out right now; at the same time, so is the argument that Mitt Romney is a callous business man and a wealthy elitist.”