The media decided that Mitt Romney would be the inevitable Republican presidential nominee weeks before voters did, according to a report that analyzes race coverage.

The study being released Monday by the nonpartisan Pew Research Center Project for Excellence in Journalism found that while Romney didn't have a clear path until chief rival Rick Santorum suspended his campaign April 10, the media concluded the race was over Feb. 28, when Romney narrowly won the Michigan primary.

The report analyzed the content and tone of coverage of the contest from Jan. 2 to April 15. It used a computer-assisted analysis of more than 11,000 news outlets and a closer assessment of 52 key print, television, audio and online news outlets.

Tom Rosenstiel, director of the Project for Excellence in Journalism and a co-author of the report, said Romney was the focus of plenty of skeptical stories throughout the primaries, but the former Massachusetts governor's victory in Michigan led to a decisive shift in media coverage. Romney grew up in Michigan, but Santorum made a strong play for conservative support.

"The press began to see Romney's victory as essentially secured by the end of February even though it was clear many voters were still uneasy," Rosenstiel said. "What we saw going on in the coverage then was a suddenly intense discussion of `delegate math' and the conclusion that no other candidate could win."

After Michigan, the report said, "news coverage of (Romney's) candidacy became measurably more favorable and the portrayal of his rivals _ particularly Rick Santorum _ began to be more negative and to shrink in volume."

Santorum would go on to win several more primaries in March, but by then the press had concluded the race was over, the report found. "In the media narrative, for all intents and purposes, the general election had begun," the report said.

The report found that none of the four major Republican contenders _ Romney, Santorum, Newt Gingrich and Ron Paul _ received particularly positive coverage, but that President Barack Obama drew more negative media coverage than any of his would-be GOP challengers.

The report found a slight drop in stories focusing on the "horse race" discussion of tactics and strategy compared with both the GOP and Democratic primary campaigns in 2008, but the number was still high. Sixty-four percent of this year's stories focused on the horse race, while 28 percent examined personal issues, public record and policy positions. In 2008, 80 percent of stories focused on the horse race.

Rosenstiel said the candidates' policy positions received greater media attention this year because there were significant differences among the candidates on important issues, especially Romney's push on health care and support for a health insurance mandate in Massachusetts.

"There were discussions about policy because there were real questions about whether tea party and social conservatives would embrace Romney," Rosenstiel said. "When Santorum and Gingrich attacked Romney on his health care plan, it raised a fairly substantive set of questions."

The report also found:

_ Romney received much more "vetting" by the press than his Republican rivals. News outlets explored matters such as his history in the Church of Jesus Christ of Latter-day Saints and experience at the private equity firm Bain Capital in at least 12 percent of their stories about the candidate. Gingrich received a similar level of scrutiny, but was the subject of only about half as much campaign coverage as Romney.

_ Santorum never received a sustained period of positive coverage despite his election victories. Coverage was momentarily positive at three points: after his strong showing in the kickoff Iowa caucuses Jan. 3; following triumphs in Colorado, Minnesota and Missouri on Feb. 7; and the week he won in Louisiana on March 24. But the positive coverage was quickly overshadowed each time by doubts about the former Pennsylvania senator's organization and fundraising.

_ Gingrich's only period of sustained positive coverage came in the week of his victory in the South Carolina primary Jan. 21. After his poor debate performances the following week and a loss to Romney in Florida on Jan. 31, coverage of the former House speaker went back into negative territory and never really recovered.

_ Paul received the most positive coverage, but also the least amount of coverage. Only 7 percent of stories featured the Texas congressman as a significant newsmaker, compared with 59 percent for Romney, 31 percent for Santorum and 30 percent for Gingrich.

_ Obama did not enjoy a single week of coverage that was more positive than negative. The negative coverage was driven by several factors, including the sustained attacks against him by the Republican field, a spike in gas prices, the uncertain pace of economic recovery and the Supreme Court challenge to his health law.

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AP deputy director of polling Jennifer Agiesta in Washington contributed to this story.

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