John W. Marshall, the secretary of public safety in Virginia and the son of the late Supreme Court Justice Thurgood Marshall, is seriously considering running for lieutenant governor as a Democrat in next year's election, he said.

Marshall, a former state police officer who also has been director of the U.S. Marshals Service, said he has told Gov. Mark R. Warner (D) that he is exploring what would be his first bid for public office. He said he told Warner in part as a courtesy and also sought the governor's advice.

"The challenge is there. It's a big decision," Marshall said. "There's a lot of factors I am considering. A lot of people have approached me."

Marshall said Warner, a first-time office holder himself, gave him advice on how to weigh the pros and cons of launching a statewide campaign, but Marshall declined to elaborate. "It was a private conversation," he said.

Warner, who is in Asia on an economic development trade mission, declined to comment. But an aide praised Marshall as a key member of the governor's Cabinet.

"Governor Warner has a very high personal and professional regard for Secretary Marshall," spokesman Kevin Hall said. "That is why he is serving as Virginia's secretary of public safety."

As secretary of public safety, Marshall advises Warner on issues of police, fire, prisons and the military. He led the administration's campaign against drunken driving and has pursued tougher anti-gang laws.

If he runs, Marshall will be competing with several other Democrats for the nomination next June. Del. J. Chapman Petersen (Fairfax), Del. Viola O. Baskerville (Richmond), former state senator Leslie L. Byrne and Sen. Phillip P. Puckett (Russell) have said they plan to seek their party's nomination.

The Democrat who emerges will face the winner of a crowded field of Republican candidates, including Del. Joe T. May (Loudoun), Sen. Bill Bolling (Hanover), Northern Virginia lawyer Gil Davis and Prince William Board of County Supervisors Chairman Sean T. Connaughton.

But several political observers said Marshall would be a formidable candidate in both the primary and the general election.

"He immediately becomes a very formidable contender" if he runs, said Robert W. Holsworth, a professor of politics at Virginia Commonwealth University. "He brings the celebrity status attached to his name. And the law enforcement issue. That's a great political pedigree."

Holsworth said Marshall could appeal to black voters, a reliable Democratic constituency, while also attracting Republicans who are impressed by his law enforcement background. Marshall spent 14 years as a state trooper and eight in the marshals service, three as its director.

"This is an armor-plated resume," Holsworth said.

Mame Reiley, head of Warner's political action committee, said it would be "historic" to have Marshall on the Democratic ticket.

"The fact that he's African American makes it exciting to have him on the ticket," Reiley said. "Thurgood Marshall was loved and respected all over the nation. I think he will bring a national interest to this campaign."

Like other Democrats in the state, Reiley was careful to also sing the praises of the other contenders, adding that "the challenge for Virginia Democrats is having to choose."

Republicans, meanwhile, said they will be ready for Marshall if he runs.

"The Republican Party has a very strong slate of candidates for lieutenant governor," said Shawn Smith, a spokesman for the state party. "We are prepared to win against whoever emerges as the Democratic nominee."

If Marshall does run for statewide office, he would be launching from the same springboard as did Jerry W. Kilgore (R), who served as secretary of public safety before running for attorney general, his current post. Kilgore is now running for governor.