MSNBC and its talk show host Chris Matthews are coming under increasing criticism as more and more details have emerged to reveal the extent of the pundit's preparations to challenge Republican Sen. Arlen Specter of Pennsylvania.

After Politico reported Thursday that Matthews had taken steps to establish residency in Pennsylvania and been advised by partisan operatives to quit MSNBC and begin his campaign, the network took incoming flak from all sides. (File) After Politico reported Thursday that Matthews had taken steps to establish residency in Pennsylvania and been advised by partisan operatives to quit MSNBC and begin his campaign, the network took incoming flak from all sides. 

"Should Chris Matthews use his air time to fawn over the voters and governor of Pennsylvania while also weighing a run for Senate in Pennsylvania?" asked Eric Burns, president of Media Matters, a liberal watchdog group. "Of course not, and these are issues [NBC News President] Steve Capus should address." 

In a strange bedfellows moment, Brent Bozell, founder of the Media Research Center, a conservative watchdog group, had a similar view.

"MSNBC has tarnished NBC's reputation so badly, that the last thing NBC needs is a new controversy caused by MSNBC," Bozell said, mentioning the perception of biased coverage during the presidential race brought on by the sister network's commentators.

NBC is maintaining a strict code of public silence on the issue, but there's only so long that network executives can brush everything off as mere rumor and innuendo.

"If he's serious about running for office, he should not be on the air," said Tom Johnson, former president of CNN. "It's a mistake, and I think it crosses the line."

Johnson, now retired from the network, is one of the only news executives who's dealt with the situation that NBC executives are contemplating now.

In November 1991, Johnson and "Crossfire" host Pat Buchanan agreed that once his vague presidential aspirations matured into a serious intention to run, he could no longer be on the air each afternoon bantering about politics with Michael Kinsley.

"Pat handled it with great sensitivity to the situation," Johnson recalled. "He and I did not have a single heated word about it. I felt that he was acting responsibly."

Matthews, on the other hand, has helped fuel speculation by meeting with Pennsylvania political leaders, talking about his boyhood dream of being a senator, publicly professing his love for the Phillies and flattering Democratic Gov. Ed Rendell on his show. Privately, he's had conversations with several political operatives to lay the groundwork for a possible run.

On Monday, Matthews' two worlds - potential candidate and talk-show host - almost collided, as he met with political insiders in Philadelphia to discuss the Senate run and then hosted "Hardball" from the city a few hours later.

As a commentator, Mathews isn't bound to the same restrictions as a network news correspondent, but there remains an ethical issue of whether he should be on television each night at the same time he is making such overtly political moves.

Tom Rosenstiel, director of Pew's Project for Excellence in Journalism, said that if Matthews started an exploratory committee, or made a formal announcement, obviously the network would need to address the situation. But there's also a question, he said, about when speculation reaches a "critical mass."

"That is one other element which a news organization needs to contemplate," Rosenstiel said. "Is there anything going on that creates a public perception problem that might be damaging the brand, or the reputation of MSNBC?"

Some observers, from both sides of the political aisle, argue the damage is already being done. "NBC's inaction on this matter is very disturbing and extremely disappointing," said Rob Jesmer, incoming executive director of the National Republican Senatorial Committee.

Phil Singer, deputy communications director for the Hillary Clinton presidential campaign and a critic of MSNBC's coverage during the Democratic primaries, created a buzz on his blog Monday by criticizing Matthews and suggesting that the network should "at the very least, [disclose] any and all deliberations and actions being taken by that person to explore a run."

"If Chris Matthews is seriously considering a run for Arlen Specter's Senate seat," Singer wrote, "he shouldn't be on the air right now."

Indeed, NBC staffers are concerned that Matthews' flirtation with the race, which has the appearance of a Democratic candidate using the network as a platform for a Senate run, could negatively affect the news division.

"Let him disprove the rumors and show how these stories are false," said Bozell.

But so far, NBC has been unwilling to comment on multiple reports, and the network's coverage of Specter and potential challengers doesn't include Matthews.

Elsewhere, though, the ethical concerns raised by Matthews' Senate machinations have been a hot topic among the political chattering class. CNN raised the Matthews rumor on the air during an interview with Specter last Sunday. On Thursday, policymakers and opinion shapers in Politico's "Arena" section sounded off as well.

For the most part, the ethical concern is not whether Matthews should run - some welcome the idea, while others are opposed - but that he has a commitment not to be a player in the political fray while simultaneously hosting a cable news show each night.

Alan Schroeder, a journalism professor at Northeastern University, wrote that Matthews would bring "some badly needed energy and intelligence" to the Senate, but that he has a responsibility to leave if he is intent on running for the seat.

"Should Chris Matthews give up his job at MSNBC if he is serious about running for office?" Schroeder asked. "Yes, though you can't blame a guy making $5 million a year for wanting to ride the gravy train for as long as he can."