A study of news coverage during the 2012 campaign so far finds that the media decided Mitt Romney was the presumptive GOP candidate on Feb. 28 after he won the Michigan primary. The study also found that Romney has received far more positive coverage than Barack Obama.

The Pew Project for Excellence in Journalism study finds that during the Republican primaries there was not one week where Obama got more positive coverage than negative. But, that's not to say Romney was a darling of the press.

From January through April, Romney's coverage was 39% positive vs. 18% for Obama.

The Daily Beast's Howard Kurtz says Romney's coverage got markedly more positive after he won the primary in his home state of Michigan.

What the research makes clear is that media outlets assumed the power to declare the race over, regardless of how many states had voted. I argued that this was happening in March, and the project’s numbers back it up. 

After Romney won his home state, Michigan, on Feb. 28, his coverage turned more favorable. Santorum’s didn’t simply grow more negative; it began to shrink. What helped Romney, says Jurkowitz, is that “the media really began to pick up on this theme of inevitable delegate math, even though he was not winning all the primaries.”

References to Romney’s accumulated delegates and electoral inevitability jumped 12-fold the week after the Michigan primary, even though Santorum would go on to win Minnesota, Colorado, Missouri, and Louisiana. The press had already pulled the plug. “In the media narrative, for all intents and purposes, the general election had begun,” the study says.