The deputy director of President Bush's drug-control office resigned Friday to explore a run for the U.S. Senate in place of Jack Ryan (search), the Republican nominee who dropped out over sex club allegations.

Andrea Grubb Barthwell (search), a Chicago-area physician, had been deputy director of the Office of National Drug Control Policy (search) in Washington since 2002, focusing on reducing demand for drugs.

Federal law barred her from seeking the Republican nomination while she worked for the government. Michael Barnes, an attorney and Barthwell friend, said she will now talk to Illinois GOP officials to gauge their interest in having her run.

"If there is an interest, she would be willing to pursue it," Barnes said. "It would be a great opportunity for her to serve."

Drug czar John Walters praised Barthwell in a statement issued after her resignation. "Her passion for protecting the health of all Americans has been inspiring," he wrote. "We wish her well in her future endeavors."

If Barthwell were chosen to face off against Democrat Barack Obama (search), it would be the first time in history that two black candidates battled as the parties' nominees for a U.S. Senate seat.

The original Republican nominee, Jack Ryan, a millionaire investment banker-turned-teacher, dropped out of the race two weeks ago, saying the release of embarrassing sex club allegations in his now-public divorce records would detract from the issues. He has yet to file the paperwork to formally remove his name from the ballot, however.

Republicans have struggled to come up with a candidate who could take over for Ryan with just four months to raise money and campaign before the election.

Many of the people who have expressed interest in the nomination have limited support among party leaders who will choose a replacement, and others with the name recognition or money to be strong candidates have turned the party down.

Barthwell is an unknown even to many leaders of the state GOP.

"Who? Don't know her," U.S. House Speaker Dennis Hastert (search) said Friday.

But others say she should be considered for the nomination.

"I've heard nothing but good things about her," said state Sen. Kirk Dillard, a member of the Republican State Central Committee.

The public attention to a race between two black candidates would help offset her lack of campaign funds, Dillard said.

Obama, a state senator, raised $4 million in the last three months, an almost unheard of amount for such a short period in Illinois.

Another possible GOP candidate is businessman James Oberweis, who finished second to Ryan in the March primary but alienated many with his attacks on illegal immigrants. And some party activists are trying to draft former Chicago Bears coach Mike Ditka, although Ditka has not said if he is interested. House Minority Leader Tom Cross, R-Oswego, emailed supporters Friday saying: "We need your help to 'Draft da Coach'."