When he stands at the gates of the American Furniture Co. here for some predawn campaigning, incumbent Rep. William Wampler (R-Va.) needs no introduction. There are no buttons on his lapels and he makes none of the stock election-year spiels.

Most of the workers know him by sight, spotting the baldish head that has earned Wampler the nickname "Bald Eagle of the Cumberlands," and they greet him with a familiarity that is the dream of every candidate. "Mornin', Bill," they say without prompting, drawing out each word with a mountain twang.

There are probably few voters left in Virginia's "Fighting" 9th District, tucked in the state's far southwestern corner, who haven't heard of Wampler, a onetime weekly newspaper reporter first elected to Congress in 1952 at the age of 26. He was defeated two years later but returned again in 1966, and every other year since.

Yet this year Wampler has had to run hard for his 10th term, raising and spending $149,000 -- more money than ever before -- in a race that some Democrats say may go their way.

His challenger, 36-year-old state Sen. Frederick Boucher (D-Abingdon), who hopes to top $200,000 in fund-raising, has put Wampler on the defensive, attacking him as an ineffective legislator and cornering him on his votes for President Reagan's economic program, particularly cuts in some Social Security benefits.

Those charges seem to stun the affable 56-year-old Wampler. "You should be ashamed of yourself," he retorted during a televised debate after Boucher attacked his record.

But in a district that includes coal fields with almost 20 percent unemployment, some Democrats are saying that Boucher's themes -- delivered with the cool analysis one might expect of a onetime Wall Street lawyer -- have successfully separated Wampler's personal popularity and his voting record in Congress.

Boucher has the support of teachers, women's groups, and more importantly, of the United Mine Workers, with 14,000 members here. He is banking on winning solidly in the hard-hit coal counties.

Even in the New River Valley, traditionally a swing area, Boucher has found that his campaign has hit home.

"I used to be Republican, I was raised a Republican," said David Stoots of Dublin, who makes a living selling socks at local flea markets. "I've always voted for Wampler. I always thought he was fine, but I can't go along this time. There are a lot of poor people who are hurting."

Boucher says his polls show him within "shooting distance" of Wampler, although even most Democrats will agree that the race is still an uphill fight.

Wampler has been an assiduous practitioner of constituent service. Not a single teen-ager graduates in the district without getting a signed certificate of congratulations from their congressman. Fifty out of 52 weekends a year, he is back home, holding meetings in county courthouses, traveling his far-flung district. In the summer, he makes the rounds of "memorials," a vanishing tradition among family clans who must wait for the warm months to mourn relatives who died during the long mountain winter.

On some issues, Wampler, the ranking Republican member of the House Agriculture Committee, deviates from the hard-line conservatism of his fellow Virginians, opposing National Right to Work legislation, for instance, and voting to send the Equal Rights Amendment to the states. Mostly, he says, he is a true believer in Virginia-style fiscal restraint who feels that this country has strayed from "fundamentals" -- like voluntary school prayer -- and who describes his opponent's record in the state Senate as "liberal," a word he uses with considerable disapproval.

On the campaign trail, Wampler falls back on his easy-going style, in between urging voters to be patient and "stay the course" with Reaganomics.

It's a manner that contrasts starkly with the more reserved Boucher who has had to rely on television to get his name known in the district. It's a difference that some say may be key to the election.

"I'm just not sure the Fighting Ninth is ready to trade in the Bald Eagle for a Wall Street lawyer," said state Republican Party spokesman Clayton Roberts.