In the four weeks since the disclosure of secret sexual-harassment settlements at the Philadelphia Housing Authority, Mayor Nutter has been largely silent.

He has held no news conferences. He has made few public pronouncements. And he has not pushed for the one change he has the power to make - replacing the only PHA board appointee he currently controls: City Councilwoman Jannie L. Blackwell.

The mayor's aides and supporters say his actions - or lack thereof - are deliberate, with Nutter resolved to await the completion of an independent investigation of PHA, which he requested, led by the U.S. Department of Housing and Urban Development, PHA's primary funder.

"The HUD investigation will bring to light all of the information needed to make a reasoned, thoughtful decision about what the next steps are. Then it will be appropriate for the mayor to be front and center," Nutter spokesman Doug Oliver said.

But the seeming absence of Nutter's voice in a controversy that has upended one of the nation's largest housing agencies has opened the mayor to criticism that he is failing to lead.

What makes Nutter's measured approach all the more perplexing is the identity of the person now speaking the loudest: former Mayor John F. Street. As PHA board chairman, Street is the official most accountable for Greene's misdeeds, and has emerged, perhaps unsurprisingly, as Greene's biggest critic. Early on, Street declared, "He [Greene] could have built a billion houses, but if he sexually harassed one woman on his staff, he's gone."

At the same time, Street has been bad-mouthing Nutter's mayoral achievements and encouraging candidates such as Sam Katz and Tom Knox to challenge Nutter in next May's primary.

"Michael has been missing in action," said lawyer Carl Singley, a former Street ally who split from the former mayor and aided challenger Sam Katz in the 2003 mayoral campaign. "The idea that he would allow John Street to upstage him on this is appalling."

Singley, chosen by Nutter two years ago to lead a commission on diversity in the construction industry, said Nutter needed to exert control, and now.

"We need to see the kind of indignation and outrage that we've seen when Mike Nutter was a candidate for office, when he was taking unpopular positions without regard to what the political implications were," he said.

While acknowledging that Nutter may be privately agitating for change, at the same time, Councilman Bill Green said, "I find the mayor's silence on this issue deafening. Frankly, I'm not sure what it is he can or cannot do, but certainly as a city councilman he was very vocal about what John Street and his administration, over whom he had no control, should be doing. . . . He has no authority in Harrisburg, but he goes up there and gets our laws changed."

In keeping with his strategy, Nutter declined to be interviewed for this article.

But Oliver and other allies of the mayor's say he would benefit little by engaging in a spitting match with Street since Nutter has no formal authority to remove him from the board.

Although Nutter technically controls Street's appointment, Street's board tenure does not end until September 2011, because he deftly inserted himself as PHA chairman during his last year in office in 2007.

"Can the mayor truly be upstaged by sound and fury?" asked Oliver, deriding Street's public comments. "We believe people prefer their leaders to be thoughtful, rational, and to act in a responsible manner."

For now, he said, Nutter is staying "above the fray."

Oliver emphasized that Nutter was out front early on when he released an Aug. 25 letter he sent to Street calling for the HUD investigation, which was announced the next day. He lambasted the board for its lack of awareness of $648,000 in settlement money for three female PHA employees. (Another case, for $250,000, is pending).

Nutter wrote to Street that "the very leadership of PHA is in doubt," and "I am baffled like most Philadelphians to learn of your contention that you as board chairman had no knowledge of the sexual-harassment cases." He added that the agency "sadly may be suffering from a lack of appropriate oversight."

But Nutter's public involvement since then has been limited. He has not called for a restructuring of the board or a replacing of Blackwell, whose five-year term expired two years ago.

Asked about Blackwell's appointment, Oliver said the mayor has spoken with the councilwoman but has made no decision about either reappointing or replacing her. Cognizant that the appointment will last five years, he is moving "judiciously," Oliver said, "to make sure he has all the necessary facts before making a decision."

Blackwell, whose dedication to affordable housing and homelessness was acknowledged also by Oliver, said she hopes to remain on the board.

"Even if he replaced me," she said, "it wouldn't give him politically or psychologically the level of control he might want to have."

The mayor's muted actions are consistent with his desire to follow process and protocol, sometimes to a fault. Critics in the past have accused him of being ineffective or slow to bring about change. For instance, rather than immediately calling for the elimination of the controversial DROP perk, Nutter first ordered a study be done that took months - and then he announced his intent to try to end the perk.

Contrarily, when Nutter has acted swiftly, he has at times found himself rebuffed and his political clout questioned. For example, last year, the seven members of the Board of Revision of Taxes publicly defied his call to resign, stirring chatter about whether he was weakened.

Of PHA's three other members, two are appointed by City Controller Alan Butkovitz, who has not moved to shake up the board. His appointees are Debra Brady, wife of U.S. Rep. Bob Brady, who is a political force as also leader of the city's Democratic Party, and Patrick Eiding, who as regional president of the AFL-CIO wields considerable influence. Eiding's appointment ends Monday, but Butkovitz expects to keep him on. The fifth member, Nellie Reynolds, is elected by the other four and is serving a term that expired in April.

City Councilman William K. Greenlee said, "Given the whole structure of the PHA board, it's not like he's [Nutter's] been in control of it. He made his statement, he made his feelings known and quite strongly, I think. . . . I'm not sure what else people expect him to do."

Councilman James F. Kenney agreed.

"This is a Street-Greene battle," he said. "I don't see where the mayor accomplishes anything by being more visible. I think there are enough investigative agencies involved. I don't see a role for him until there are some results."

As for replacing Blackwell, known on Council as a maverick, Kenney said Nutter would be putting his Council priorities at risk.

"If you remove her, you're creating potential havoc for yourself with the rest of your agenda, and giving yourself more grief with this legislative body, which he doesn't need right now."