When he took on one of his party's most popular state delegates and very bested him in a close Republic-Congressional primary, Frank R. Wolf created a small sensation in Virginia's 10th District. Now, two years later, he's doing it again.

Aided by his own energetic campaigning and by what his current Democratic opponent calls "just oodles of money," Wolf, an Arlington lawyer who has never held an elective office, is making a surprisingly strong race against Rep. Joseph L. Fisher.

"I think this election will be a lot closer than people think," said Jeff Gregson, executive director of the State's Republican Party. "Nobody really gave Frank Wolf much of a chance up there six months ago, but he seems to have picked up some of the undecided vote and is looking stronger in the past three weeks," Gregson said.

It would be an overstatement to say the 39-year-old scrappy Republican challenger has the highly-required two-term Democratic incumbent running scared, but Wolf is definitely making an impact on what had previously been expected to be an easy reelection bid for Fisher.

His campaign literature is everywhere in the 10th District - an area that comprises Arlington, Falls Church, Fairfax City, northern Fairfax County and Loudoun County. Wolf's campaign manager, Carole Cones, estimates that more than 650,000 pieces will have been distributed by mailings and "door-to-door blitzes" by the Tuesday election.

Using the literature and frequent radio and television spots to pitch his messages to the District's 243,514 registered voters, the former congressional aide and Interior Department official has one central campaign theme: Joe Fisher is too liberal for the area he represents.

"Joe Fisher doesn't vote the way he talks," is Wolf's favorite phrase and one he has used to the incumbent's annoyance whenever the two have met in their frequently acrimonious debates.

"Is he rally for us?" queries the headlines on a Wolf campaign flier that attacks Fisher's voting record on such sensitive subjects as taxes, inflation, civil service reform, defense spending, constituent services, aid to senior citizens and support for President Carter.

If elected, Wolf has said he will seek "a real tax cut," push for increased federal spending for Metro and future construction of above ground, open air stations, oppose District of Columbia voting representation in the Senate (but not the House), fight a D.C. commuter tax; try to do away with congressional perquisites and see that federal equal employment and safety regulations are applied to congress; and "have the courage to say 'No'" to increased federal spending.

Wolf, classifying himself as a moderate-conservative, has accused Fisher of trying to "hide" from his voting record so that his constituents won't realize that he "is a very liberal congressman."

While some political observers have decently suggested that Wolf has misjudged the district, projecting a more conservative image than is apt for the area, GOP stalwarts disagree.

"I don't think his conservative stand is going to hurt him," said Gregson, noting that Wolf is seeking election in a district that sent conservative Republican Joel T. Broyhill to Confor 22 years before Fisher defeated him in 1974.

Wolf's hard and fierce, well-financed campaign - he is outspending Fisher nearly two to one, $190,427 compared to 97,734 according to a recent financial report - is new to 10th District Republicans.

"I've never seen anybody work as hard," said Edmund Walton, the former 10th District Republican chairman. He recalled how party regulars were impressed in the Republican congressional primary two years ago when Wolf gave Del. Vincent F. Callahan Jr. "the scare of his life," losing to Callahan by only 562 votes.

Wolf is trying to do the same to Fisher but is finding that the latter's "grandfatherly image" with voters - he is 64 - is a buffer against agressive campaigning. What Fisher calls Wolf's "attack, attack, attack" style is to some a disconcerting departure from traditional, gentlemanly campaign demeanor in Virginia.

"I'm not really an aggressive person, but I'm running against an incumbent," said Wolf, who has estimated that congressional service budget, franking privileges and exposure as an office-holder is worth about $1.2 million, much more than either candidate is actually spending on the campaign.

A Philadelphia native and the son of a retired policeman there, Wolf moved to Northern Virginia about 17 years ago after graduating from Penn State University. He received his law degree in 1965 from Georgetown University. Before establishing a private Rossyln law practice in 1975, he was a legislative assistant to former Rep. Edward G. Biester Jr. (R-Pa.) and served as deputy assistant secretary for congressional and legislative affairs for the Department of Interior.

Several congressional staffers who knew Wolf when he worked on the Hill during the Nixon and Ford administrations say he did a very good job in his liasion duties. The experience, according to Wolf, gave him "a real drive" to serve in Congress himself.

Lately, however, some of Wolf's feistier charges have misfired, such as recent allegations that Fisher bused in organized labor supporters from Baltimore and Philadelphia in 1976 to distribute literature and that he is using a paid congressional staffer to work in his campaign. (The staffer is on a leave of absence from her Hill job, and Wolf could not provide specific details about the alleged outside precinct workers.)

"Frank was really one of the best congressional liasions for the Interior Department," said Tom Morr, a staff member of the House Government Operation Committee. "He was very competent at what he did. I think Frank understands Congress both from an administrative and legislative way of things."

But Louise Dunlap, director of the Environmental Policy Center, remembers Wolf as someone "who worked diligently to carry out the policies of an administration that was working to scuttle major environmental and energy legislation" designed to control strip mining and off-shore drilling, issues that both affect Virginia. end insert.

Wolf considers himself as experienced on the Hill as Fisher and says he wants to be in Congress "because I'm now overly impressed with the kind of commitment we have there now."

Since opening his law firm, Wolf has been a registered lobbyist for such firms as the National Farm and Power Equipment Dealers Association and Gerber's Baby Food. But he says he registered to avoid violating "the spirit of the law" and has spent little time directly lobbying any legislators.

Calling Fisher "part of the club" in Congress, Wolf said legislators who serve too long become cynical. Wolf would limit them to 12 years total in office.

"After 12 years, I will leave," Wolf has promised. "Otherwise, you lose the idealism that makes you a good congressman."