In the old days it mattered but not now.
For starters newspapers USED to be owned individually for the most part. Now it’s rare to find an independent paper. So the endorsment is likely to come from the head office, not the paper. The Chicago Tribune for instance, owns the LA Times.
Newspapers also endorse later than they used to? Why? Because corporations suck up to Obama as they see him the winner.
Currently the FCC prohibits newspapers and TV stations from a common owner in the same market. With some grandfathered exception. So a company like the Tribune with newspapers and TV in the same market is unlikely to endorse McCain as he will lose and it won’t help them to lobby Obama to change the law.
Newspapers and TV stations are acting in the self interests
Also remember the Chicago Tribune is under new ownership. It’s owned by a venture capitalist and the goal is to make money, not to publish a newspaper. It’s like investing in Google, not because you want to own a piece of the company but rather 'cause you want to make money