Friends of White House deputy drug czar Andrea Barthwell sent a letter to the Illinois Republican state central committee arguing that she represents the party’s best hope of defeating state Sen. Barack Obama (D) in the state’s Senate race this fall.

“Dr. Barthwell’s public record is one of which the Illinois Republican Party and the voters of Illinois can be proud,” Illinois Republican John Gilligan wrote in the missive. “As a Senate-confirmed Bush appointee, her criminal and financial records have been subject to public scrutiny for over two and a half years.”

Gilligan’s statement is a tacit reference to the failed candidacy of former investment banker Jack Ryan (R), who dropped out of the Senate race last week after lurid details of his private life were released in child-custody records.

Ryan’s departure from the race puts the power to select a new nominee in the hands of the 19-member state central committee, which includes a representative from each of the state’s Congressional districts.

While Illinois Republicans consider their options, National Republican Senatorial Committee Chairman George Allen (Va.) expressed confidence Thursday that the eventual GOP nominee can be competitive with Obama in the fall.

Although the state committee has until the end of August to select a candidate, informed sources expect the process to conclude within the next three weeks.

If Barthwell was selected by the committee, it would mark the first-ever Senate race between two black candidates.

That possibility appears to be a long shot, however, according to one knowledgeable Illinois Republican.

“She is a complete unknown who has made no effort to reach out to people in Illinois or the committee members and party leaders who will ultimately make this decision,” said the source.

Among the names mentioned as possible replacement candidates for Ryan are state Sen. Steve Rauschenberger, dairy magnate Jim Oberweis, paper company executive Andy McKenna and former state Board of Education Chairman Ron Gidwitz. Gidwitz is also the current finance co-chairman of the Illinois Republican Party.

McKenna, Oberweis and Rauschenberger were all runners-up to Ryan in the March GOP Senate primary.

Much of Barthwell’s apparent reticence to explore a candidacy is due to the constraints of the Hatch Act, which prohibits federal employees from running for partisan office or engaging in overt political activities.

“While I am certain that Dr. Barthwell would relish the opportunity to serve the people of Illinois in the United States Senate, she is best advised not to discuss such opportunity with political decision makers while she remains subject to the Hatch Act’s restrictions,” wrote Gilligan.

Barthwell was nominated to her current post in December 2001 and confirmed in late January 2002. Prior to her service in the Bush administration, she had a private medical practice in the Chicago area.

At a Washington, D.C., news conference Thursday, Allen acknowledged the “very unusual situation” facing Republicans in the Illinois Senate race, but said he believes the party has some hope.

“We’re not writing off Illinois at this point,” he said. “What we’re doing is waiting to see who’ll be selected.”

Allen noted that the eventual nominee will be selected before Republican Senate nominees are chosen in a handful of competitive states with late primaries, giving the candidate plenty of time to illuminate his or her differences with Obama, a liberal state lawmaker from Chicago.

“In lots of states, neither side knows [yet] who the nominee is going to be,” Allen said.

But Allen refused to say how much money the NRSC is willing to dedicate to the Illinois race, and he refused to comment on the sniping that is taking place between retiring Sen. Peter Fitzgerald (R) and Illinois GOP leaders in the wake of Ryan’s withdrawal.

“I’m not going to get into the business of criticizing or making comments,” he said.

Josh Kurtz contributed to this report.