Dan Hurd and George Reaves stood in the corner of the crowded, smoky storefront office and speculated why a Northern Virginia congressman would drive 210 miles from his home to dedicate a local Democratic Party headquarters.

"What's he running for?" asked Hurd, an area representative of the National Association of Government Employees, nodding toward Rep. Herbert E. Harris II (D-Va.).

Harris was speaking with electioneve fervor to the crowd of 60, most of whom were union officers or party activists, about "the need to build a Democratic Party for the 1980s."

The rousing speech -- to an audience drummed up by Harris' staff -- was just one of a dozen public and private appearances by the 8th District congressman during a whirlwind, 48-hour tour of Tidewater Virginia last Sunday, Monday and Tuesday.

Coming on the heels of his sixth trip to Richmond in six weeks, Harris' stumping here inevitably led to the question of why he was doing this.

Why, he just happened to be in the neighborhood for a congressional hearing, said the 52-year-old thirdterm liberal from Fairfax County with a grin. And as a loyal party member, Harris said he wanted to help out any way he could.

That is what he told political science students at the College of William and Mary in Williamsburg, the Virginia Port Authority board in Norfolk, interviewers on talk shows on three television stations and editiorial writers at the area's two major daily newspaper combines.

But what nearly everyone who heard him suspects is that Harris is gearing up for a 1982 race against independent Sen. Harry F. Byrd Jr.

Because many Virginia politicans view running against Byrd as a losing cause, Harris, by starting early, might be able to win his party's nomination without one of the debilitating intraparty battles that have hampered recent Democratic nominees for statewide office.

When Harris showed up for the congressional hearing Monday at NASA's Langley Research Center, Rep. Paul Trible, the local Republican congressman, asked a reporter, "Are you here covering the Senate campaign?"

If Harris' public meetings were not enough to whet political appetites, his private meetings offered a smorgasbord for rumors: breakfast with Henry E. Howell, the former lieutenant governor and titular head of the party's liberal element; lunch with Portsmouth Mayor Richard J. Davis, the new Democratic state chairman; dinner with Homer Cunningham, a moderate Democrat and successful businessman, and an afternoon chat with former Sen. William E. Spong Jr., dean of the law school at William and Mary, and who except for two lieutenant governors, was the last Democrat elected to statewide office in the Old Dominion since 1966.

Even as Harris denied speculation about his motives, he fueled the rumors with remarks such as, "I do know the date of the election, don't I?" Three aides who accompanied Harris, administrative assistant Christopher J. Spanos, legislative assistant Charles Nance and press secretary Jack Sweeney, joined in the teasing, calling out "Here comes the candidate," or, to the lone reporter who was trailing them, "The press bus leaves in five minutes."

For the record, Harris insisted that all of his meetings here were to gather support for pet projects, such as getting blacks and women named to the federal bench in Virginia, and getting the machinery in place for upcoming elections, beginning with the 1980 presidential campaign.

"Democrats have to start acting like Democrats," he said to cheers at the meeting in the party headquarters here. "We can't be as reactionary as the Republicans, because if we are, they'll beat us every time."

So while Harris is staking his future on the idea that a moderate-to-liberal Democrat can be elected in Virginia, he favors imitating the GOP when it comes to putting together a campaign.

"Virginia Republicans spend $400,000 a year on staff, technology and computers," Harris told a William and Mary student in answer to her question of why Democrat Andrew P. Miller lost last November's Senate race to John W. Warner. "They started that campaign -- as they do all of them -- at a gallop," Harris added.

While Harris insisted his tour of the heavily populated Tidewater area was not a political fishing trip, subtlety is not his long suit, and everywhere he went, the scent of a campaign-in-the-making was detected.

After listening to his speech at William and Mary, one student, Edleen Pawloski from Vienna, said, "It sounds like he's up to something."

Lynn Fischer, who interviewed Harris on the NBC affiliate here, asked "What are you doing on a talk show in Tidewater?" Then she answered her own question, saying: "It has the look and feel of a campaign."

Becky Livas, another Tidewater talk show hostess, noted that "This is not an election year. Congressmen are not running." Then she asked Harris what he could possibly know about "Byrd country."

The Byrd machine, which once ran the state's politics, responded Harris, "exaggerated the differences in the various parts of the state -- an old shibboleth created by an old machine," he said. Harris said he has detected "a comity of interest in the growth areas of the state," which he identified as Tidewater, Richmond, Roanoke and the Virginia suburbs of Washington.

If there is a strategy in the making for a 1982 Senate race by Harris, it would appear to be to concentrate on those four heavily-populated regions.

When it was pointed out that he had not visited Roanoke recently, a Harris aide quipped, "It's lovely in the spring." Harris insisted he has "no plans to visit Roanoke." And then he broke out in his boyish grin and added, "Unless, of course, my duties take me there for a congressional hearing."