The only Sunday morning talk show Mitt Romney has appeared on this election season is Fox News Sunday, and the other networks are annoyed that the Republican presidential candidate is ignoring their invitations. "I know he does Fox," Bob Schieffer said to senior Romney adviser Ed Gillespie on CBS's Face the Nation this weekend, "but we'd love to have him some time, as would Meet the Press and the ABC folk, I would guess." Gillespie replied: "We're going to take our message to the American people. You saw him talking to schoolchildren last week." And it's not just the Sunday shows Romney is avoiding. Aside from two sit-downs alongside his wife, Ann — on CBS and ABC — and appearances on CNBC and CNN, Romney has only talked with Fox News since securing the GOP nod nearly two months ago. Why is Romney sticking with the "fair and balanced" network? Here, five theories:

1. He only wants softball questions

Romney is following the lead of other conservative Republicans, says Joe Gandelman at The Moderate Voice, "using Fox News as a way to avoid having to answer those pesky, non–public relations, non-softball questions and follow-up questions that he'd get on CBS, NBC, ABC." Much like Sarah Palin, he has "had a hard time in other interviews beyond Fox," says Ron Chusid at Liberal Values. Romney doesn't like to get into specifics on his secret plan for the economy or why his Bain Capital record is an asset, and heaven forbid "clips of his past statements were brought up."

2. Romney learned his lesson from the primaries

Sticking with Fox is a deliberate strategy by Team Romney "to limit national media exposure this time around," says Michael Calderone at The Huffington Post. Romney did the Sunday shows and magazine profiles in 2008, and his GOP rivals "made the weekend rounds" this year, and how well did any of that work out? After the contentious primary, Romney has "benefited from learning the importance of hammering home a singular message on safe turf," says Justin Sink at The Hill.

3. He's still shoring up his right flank

Team Romney is working hard to strengthen its bridges to the Right, and Fox News is just part of that strategy, says Calderone at The Huffington Post. Along with his two appearances on Fox News Sunday, the former Massachusetts governor recently held an off-the-record meeting with "dozens of conservative columnists, reporters, and bloggers," followed by interviews last week with two of the sites represented at the meeting, Hot Air and Townhall. One attendee at the private sit-down said Romney's message to conservatives is "we want you on our side and working with the campaign."

4. He has no reason not to stick with Fox

Appearing on Fox News gives Romney a lot of advantages, says The Moderate Voice's Gandelman. Like other Republican candidates, he is almost guaranteed as much air time as he wants, "where the candidate can regurgitate talking points" in front of huge amounts of right-leaning voters. Plus, if he makes a verbal misstep, "more likely than not his interviewer would gloss over the gaffe, try to discreetly explain it away, and re-ask the question." It's smart PR, and today, unlike a decade ago, "Romney can get away with it."

5. He's getting bad advice

Can you really "run for the presidency more or less exclusively through Fox News?" says Richard K. Barry at Lippmann's Ghost. Maybe: After all, the only people who really pay attention to public affairs programs are political junkies and reporters. But "I think it is foolish to try." Not only is it risky to alienate reporters who help shape the campaign narrative, but I doubt ignoring the press "plays well with the mainstream of the country, the kind of people you need to vote for you outside your conservative base if you hope to win the presidency."