A political strategist who steered Senator McCain’s upstart bid for the Republican presidential nomination in 2000, Michael Murphy, may soon take a prominent role on Mr. McCain’s campaign for the White House, though even some advocates of Mr. Murphy’s return aren’t sure how or whether such a move would work.

Republican operatives who asked not to be named said Mr. Murphy, 46, had offered to work for Mr. McCain. However, the sources said it was unclear how much authority the message crafter and advertising guru would be offered and whether it would be enough for him to accept a role.

The talk of Mr. Murphy’s imminent return to Mr. McCain’s side was fueled yesterday by the lack of any denials from those said to be involved. The usually garrulous Mr. Murphy did not respond to telephone and e-mail messages seeking comment.

A spokesman for Mr. McCain’s campaign, Tucker Bounds, also had little to say. “I have no announcement to make,” he said in an e-mail message to The New York Sun.

“These were changes that should have taken place back in March and April,” a Republican presidential campaign veteran said yesterday. “McCain needs to do something to shake things up. A lot of Republican political people were out over the weekend saying he needs to do something to change the subject: Bring in Murphy.”

The possibility gained more currency yesterday after a prominent conservative, William Kristol, wrote in a New York Times column that he expected that “in the next couple of weeks we’ll learn that Murphy is coming on as chief strategist.”

Mr. Murphy was known as a jocular, sharp-witted sidekick to Mr. McCain during his unsuccessful primary bid in 2000. The message guru is also highly regarded for his ability to produce ads that helped Republicans, such as governors Schwarzenegger of California, Romney of Massachusetts, and Whitman of New Jersey, win election in Democratic-leaning states.

Mr. Murphy sat out this year’s presidential primary campaign because of his ties to both Mr. McCain and Mr. Romney.

A Democratic strategist who worked for Senator Kerry and Vice President Gore, Chrstopher Lehane, said a formal role for Mr. Murphy would signal a major change in Mr. McCain’s message. “The campaign has been following a very puzzling approach, which is to play into the Democratic message that makes clear this will be a third Bush term. If Murphy is involved you’ll have a completely different strategic approach. They’ll combine McCain’s unquestionable personal courage and valor shown in that prison cell in Vietnam … with the perception that he’s shown courage over his career in public office,” Mr. Lehane said, though he added that he doubts this year’s campaign will be decided based on the advice any candidate receives.

The chief concern expressed about Mr. Murphy’s arrival is that he might be an awkward fit with an operative from President Bush’s 2004 campaign, Steve Schmidt, who took over day-to-day operation of Mr. McCain’s campaign just last week in response to concerns that the operation was listless and failed to capitalize on a three-month head start over the Democrats.

“I don’t know if it could work or it could be incredibly combustive,” a regular surrogate for Mr. McCain’s campaign said of the potential pairing. “Steve is much more of a rapid fire, relentless, hammer-the-message-home-until-everybody-gets-nauseous, only-then-is-it-really-getting-through kind of guy. I think Murphy gets rapid-fire but he’s very much into stagecraft and bigger thematic messages.”

Mr. Schmidt has begun trying to keep Mr. McCain on message and to limit the diversions caused by his accessibility to the press and public, all while preserving the candidate’s reputation as a “straight-talking” reformer. Mr. Murphy helped craft the freewheeling approach that the campaign is now trying to rein in.

A political analyst who observed Mr. Murphy and then Mr. Schmidt execute campaigns for Mr. Schwarzenegger said she is doubtful the two aides could be given equal stature. “I don’t see a co-campaign manager dynamic working out,” Sherry Jeffe of the University of Southern California said. “If Murphy comes in only to do the media, if they cut that piece off and that’s his, that’s one thing, but I don’t think it’s helpful to have two people calling the shots.”

Mr. Murphy has clashed with other advisers and insisted on near total control of the campaign operation, including during Rick Lazio’s 2000 race against Senator Clinton. “That was a campaign where he very clearly wanted to be the general,” a Republican operative who handled strategy for Mr. Lazio, Rick Wilson, said.

In a 2005 interview, Mr. Murphy acknowledged that he has little patience for dithering and campaigning by committee. “I’ve been in campaigns where there’s some big, kind of U.N. debating society, and they were a disaster,” he told the Boston Globe.

Mr. Wilson said Mr. Murphy could come on board to handle message issues, while leaving get-out-the-vote and state-by-state organizing to Mr. Schmidt and another former Bush aide who recently came aboard after working on Mayor Giuliani’s presidential primary campaign, Michael DuHaime. “You don’t necessarily need a Mike Murphy turning the dials every day,” Mr. Wilson said.

Mr. Murphy could run into some trouble from Mr. McCain’s policy against lobbyists in official campaign positions. While Mr. Murphy is not a registered lobbyist himself, his firm, DC Navigators LLC, has lobbied for dozens of clients including Indian tribes and pharmaceutical companies.