Some of his prized mailing lists are for sale, minimum bid $200,000. Dozens of his employes have been laid off. Some of the causes he championed have been placed "on the back burner."

Richard A. Viguerie, the fund-raiser whose direct-mail empire in Falls Church has helped fuel numerous conservative causes, says his business is off by nearly 40 percent from last year, a decline he says represents the expected falloff from a presidential year and his time-consuming campaign for the Republican nomination for Virginia lieutenant governor.

Other direct-mail operatives in the Washington area -- working for a number of conservative causes -- say they , too, are facing a steep decline this year. Some say the drop could signal troubles for the massive fund-raising appeals that Viguerie popularized in the past decade.

Michael Gretschel, who runs List America in Washington, said Viguerie's recent offer of up to 2 million names from his files is "not a hot commodity" because of a widespread belief that conservative mailings may have reached their peak.

"They're [Viguerie's] company having financial troubles, that's fairly commonly known," said Gretschel. "Conservative fund-raising is in the pits right now."

He and other conservative fund-raisers said that the successes of a man most conservatives adore -- President Reagan -- have hurt their efforts. "The president has lulled the conservative activists to sleep," said Gretschel.

"Everything was so good last year we didn't expect it to be so bad," said Ann Stone, who heads a national fund-raising firm in Alexandria. "You'd think we get smart enough to plan for it."

Viguerie said his businesses have been hurt by his campaign for lieutenant governor, a race in which most Republican politicans say he is the third of five candidates. Viguerie said in a statement today that he expects to win with the help of delegates he will pick up this weekend in the Norfolk area. The meetings there have called "Super Saturday" because they will select 429 votes to the state GOP nominating convention May 31-June 1.

"My issue-oriented campaign has caught on with Virginia Republicans and is going to lead us to a resounding victory around the state," he said. His campaign is said by many Republicans to be trailing those of former state attorney general J. Marshall Coleman of McLean and state Sen. John H. Chichester of Fredericksburg. Even if Viguerie's campaign, his first in Virginia, fails, he could emerge as a power broker at the party convention, many say.

Viguerie has acknowledged that because he is well known as a fund-raiser, he has attracted more attention than some of his four Republican rivals. "People want to read more about Richard Viguerie than Joe's shoe company," he said, declining to discuss his business in detail. "We're doing 40 percent less than we did a year ago. Why keep 40 percent overhead?"

His firm, Richard A. Viguerie Co., systematically has cut its staff of nearly 300 since last year, according to former employes. Previously, Viguerie said he did not cut his staff significantly during slumps. "Quite frankly the cuts are to reflect more realistically the market place."

Publisher of the Conservative Digest, Viguerie said he recently sent out only the second fund-raising request for the magazine in its 10-year history.

Subscribers will soon be asked to make up the costs of the magazine that he has carried, he said.

Former Viguerie aides and associates say Viguerie is cutting back his interest in dozens of groups he has helped formed.

For example, the Populist Conservative Tax Coalition, Inc., a group formed last year and funded largely by Viguerie, has been placed "on the back burner," one Viguerie associate said. It originally was to recruit 1 million members and hold a national convention to fight for fair taxes on a budget of $1 million.

Earlier this year, Viguerie acknowledged problems with two large, conservative clients, the Washington-based Ruff-PAC and National Conservative Political Action Committee (NCPAC) of Alexandria, one of the biggest fund-raising PACs in the country.

He pointed out that his businesses are not alone in their troubles.

One of the biggest mass-mailing snafus came earlier this year when the Republican Senatorial Campaign Committee lost $4.5 million on its January mailing of more than 20 million fund-raising letters.

"The mailing lists are overmined," said Charles H. Dolan, executive director of the Democratic Governors Association. The conservatives are "hitting the same lists again and again and again," he said. "It was a novelty five years ago, but when you get two or three letters a week . . . you're saturated."

Fran G. Gemma, whose Washington public relations firm specializes in conservative organizations and has worked for Viguerie, suggested the days of millions of letters may be giving way to "more specialized, targeted groups of 25,000 to 100,000 people."

Viguerie said Thursday that a $1,500 per-person dinner May 16 to honor Reagan and Vice President Bush at the Washington Convention Center was about 40 percent off in expected ticket sales.

Richard Galen, a spokesman for the dinner, said, however, the dinner is the same price as last year and would exceed last year's gross of $4.7 million. He declined to say how many tickets have been sold.