As his driver sped down 17th Street, John McGlennon, a professor at the College of William and Mary and Democratic candidate for Congress from Tidewater Virginia, spotted the headquarters of the Daughters of the American Revolution and had a thought.

"I wonder if the DAR has a PAC," mused the 33-year-old political scientist who began PAC-hunting only seven weeks ago and was still getting used to the rules of the game.

McGlennon was in Washington foraging for contributions from political action committees, one of hundreds of candidates streaming through the city, meeting with the people who try to pick winners from losers and then put their money where their bets are.

What the Williamsburg professor learned was that Washington PACs are not good hunting grounds for nonincumbents. The nation's 3,479 PACs reported last week that for every dollar they have given to challengers this year, they have given seven to incumbents.

But those odds haven't stopped long-shot candidates like McGlennon from making the rounds. When he drove by the DAR's Constitution Hall last week, he had already been to see the Operating Engineers and the International Brotherhood of Electrical Workers. By the time he left the next day to return to his district three hours away, he had touched base with eight PACs -- from CLIC (Carpenters Legislative Improvement Committee) and MORPAC (mortgage bankers) to groups for Savings and Loans, the Seafarers, teachers and Democrats for the 80s, nicknamed Pam-PAC for its founder, Pamela Harriman.

This was McGlennon's second visit to the PACs since July. A gangly, mild-mannered bachelor who looks more like a Scout leader than a television-era politican, McGlennon was catapulted into the race this summer after his academic colleague, state Del. George Grayson (D-Williamsburg), suddenly dropped out, complaining of nervous exhaustion. Grayson's withdrawal erased the Democrat's eight-point lead over Republican state Sen. Herbert Bateman in the election to replace Republican Rep. Paul S. Trible, who is running for the Senate.

The Grayson episode sent the Democrats reeling. For McGlennon, a district party chairman who had never sought elected office, it meant starting a campaign from scratch. After Grayson withdrew, some PACs -- including the Seafarers -- demanded their money back. And the AFL-CIO's political arm, which had targeted the district early on, immediately dropped it from its so-called "marginal" list.

Getting back on that list was one of McGlennon's initial tasks. On his first trip to Washington, he went wooing members of the AFL-CIO's House campaign committee. He also checked in with other traditionally Democratic groups, including PACs put together by Democratic presidential hopefuls and the National Committee for an Effective Congress.

It was a successful mission. The unions, swayed by the 1st District's history of supporting Democratic candidates (Trible was an exception), its 31 percent black vote and its 40,000 union members, put McGlennon back on their list.

And while some of the other PACs have not given him money (yet, he notes optimistically), McGlennon felt he had made his point. "Washington is a small town," said McGlennon. "You want people to talk about you. Sometimes you don't know whether you're going to get anything, but you want them to talk."

This time, McGlennon was talking to individual union PACs, business PACs and anyone else willing to hear how a little-known college professor was going to beat a well-financed Republican lawyer. McGlennon has already shed some of his academic image, shaving off a beard, trading in his small foreign car for a two-year-old Buick Skylark.

With almost every PAC, McGlennon had to try explain away his handicaps, laughing painfully whenever the subject of Grayson's exit came up.

"I've had people tell me that he sat in their offices asking for money the day before he dropped out," he told one union representative. "It was a shock to me, too."

For the doubters, McGlennon had a short litany: The crisis this summer had helped pull the Democrats together and, while he had never held office, he also didn't have a record that Republicans could tag as liberal. He went on to describe his self-produced radio ads, knocking Bateman's theme that the sagging economy is the Democrats' fault; his fund-raising efforts back home ($40,000 so far), and his nonstop campaigning through a district that covers both sides of the Chesapeake Bay.

"I've been to the Northern Neck 10 times and the Eastern Shore 3 times," he would tell the PACs. "I'm sure my opponent can't say the same."

By the end of the day, the litany had been refined slightly. At his 10 a.m. appointment, McGlennon was gloomy about his chances of financing a TV blitz. "Don't tell them that," warned one union representative. Later, McGlennon simply nodded when other PACs reminded him of the importance of television. "I would say I'm a fast learner," he said later.

Throughout the day, McGlennon got tips on PAC-protocol. The unions all insisted on endorsements from their local business agents; some wanted to see some action from the state AFL-CIO president. "His letter will be read," said one PAC representative.

All stressed the importance of lobbying. "I get mailings from some candidates every day. I may not read them, but I notice," said Chris Gersten of the Operating Engineers. "It is the old matter of the squeaking wheel."

The meetings also offered an opportunity to exchange political gossip. At some stops, there was as much interest in news about Virginia's Senate race as about the McGlennon's district.

McGlennon was also warned about a late-October media blitz some PAC officials said they expect from Republicans across the country. "My hunch is you will see so much money dropped by Republicans in the last days that it will make your hair stand on end," said Peter Fenn, executive director of Democrats for the 80s, during a chat in his Georgetown office.

For McGlennon, as for Grayson before him, begging money from the PACs is a troublesome process. But the professor resisted judgments that might sound like a classroom lecture. "There is an expectation that a political scientist who is actually involved in the process will be shocked," he said. "Actually, I expected more of them to expect commitments in return. In that respect, it's easier than I thought."

For the PACs, there remained the critical question of whether McGlennon is a winner. "He doesn't look like a candidate for Congress," admitted one representative privately. "That's hurting him . . . . In the end, it's always subjective."

Indeed, most of the PACs left McGlennon with promises of consideration, but little cash. "He has a ways to go," said one union representative. "He has got to sell himself."

"Too many nonincumbents think that money grows on trees here," said Evan Zeppos, spokesman for the Democrats Congressional Campaign Committee. "There is an awful lot of competition for that PAC money. Somewhow the District of Columbia has this image that this is where the financial support is. Perception is one thing; reality is another."