Traditionally, the state's senior senator of the president's party, in this case Sen. Bob Casey, makes a recommendation to the White House. However, when longtime Republican Sen. Arlen Specter switched parties last April and became a Democrat, that complicated the selection process, sources said.
Sources said that Casey and Specter could not agree on a single candidate to recommend to Obama, who makes the formal nomination.
An initial screening process last summer produced a list of 20 names for U.S. attorney here.
With Casey and Specter unable to settle on one, several names were jointly submitted to the White House last month, sources said.
A source with knowledge of the matter declined to say how many names were submitted or to identify them.
Among those thought to be on a short list, sources said, are Cheryl A. Krause, a partner at Dechert LLP; James J. Eisenhower, a partner at Schnader Harrison Segal and Lewis LLP; and J. Huntley Palmer of JP Morgan Chase & Co. All were once federal prosecutors here.
Krause, Eisenhower and Palmer declined to comment for this story.
Justice Department spokeswoman Melissa Schwartz would neither confirm nor deny whether the Justice Department had received any names from the White House or begun vetting any candidates.
Larry Smar, a spokesman for Casey, said, "As of right now, I don't have a sense of when a nomination will be made."
A spokeswoman for Specter declined to comment.
The U.S. attorney here - one of 93 in the country - brings criminal and civil actions on behalf of the federal government in the nine-county area of southeastern Pennsylvania.
The office has prosecuted a number of high-profile public-corruption cases in recent years, including that of former state Sen. Vince Fumo and former City Councilman Rick Mariano.
Former U.S. Attorney Meehan resigned his post in July 2008. The current U.S. attorney, Michael L. Levy, was named by the Justice Department on an interim basis last May to serve as U.S. attorney until Obama nominated a successor.
When the White House receives a senatorial recommendation, it is sent to the Justice Department for vetting.
Schwartz said the vetting process - which includes background checks and interviews by political and career officials - can typically take up to three months.
Once a finalist is determined, that person is interviewed by Attorney General Eric Holder, who makes a recommendation to Obama.
After Obama makes the formal nomination, it is sent to the Senate for confirmation.
And there's no certainty that a nominee - given the current partisan rancor in the Senate - will win timely confirmation.
Case in point: New Jersey's new U.S. attorney, Paul Fishman, was recommended to Obama last February and was nominated by the White House in May, but not confirmed by the Senate until Oct. 7.
According to the Web site Main Justice, an independent news organization that covers the Justice Department, 31 new U.S. attorneys have been confirmed by the Senate, 12 more have been nominated by Obama and another 23 names have been recommended by senators to Obama for U.S. attorney posts throughout the country.
None of those confirmed or nominated to date are holdovers from the Bush administration, although two Bush holdovers have been recommended to Oba-ma.