The U.S. Chamber of Commerce, a long-standing voice of fiscal and monetary conservatism, has spent its way into financial trouble carrying out an ambitious program to spread its views of business and politics.

The chamber's most recent financial statement shows that its capital fund of securities dropped by 26 percent between 1980 and 1981 and its operating deficit more than doubled to nearly $10 million in that period.

As a result, the chamber's board of directors, gathering today for its quarterly meeting, will be asked by President Richard L. Lesher to undertake an extraordinary $35 million capital-raising program. According to chamber executives, about $7 million already has been collected by a professional fund-raising organization, however.

This is only the second time in its 70-year history that the chamber has turned to its members for such help. The last time was in the early 1920s, when the chamber needed capital to build its massive Indiana limestone headquarters, which sits across Lafayette Park from the White House.

The chamber's current direction was set by Lesher, a former NASA official who became chamber president in 1975. Lesher is credited with building the chamber into a communications conglomerate. But he has stirred controversy among members by throwing these resources behind the supply-side economic policies of the Reagan administration. Lesher was not available for an interview until after today's board meeting.

The chamber's finances also have become controversial within the chamber and reportedly among its board of directors.

To spread its views of Washington to its members in business and industry, the chamber under Lesher has expanded and actively marketed its publications -- "Nation's Business," its monthly magazine, and "Washington Report," the weekly newspaper that reports on the chamber's political friends and foes.

Its most significant investment -- and biggest cash drain -- is its recently completed $4 million TV studio, which beams news and political reports to subscribers by satellite. Says Thomas J. Donohue, group vice president in charge of development: "This institution has changed dramatically. The foremost thing we are is a communications organization."

But the costs of these ventures shot upward at the very time the economy was slipping into a prolonged swoon. A review of the chamber's financial statements shows the consequences: It is spending more money than it is taking in, and at an increasing rate.

In 1981 expenses exceeded revenues from operations by $9.8 million, up from gaps of about $4.4 million in 1980 and $28,000 in 1976. Faced with these growing deficits, the chamber has dismissed about 30 employes in recent weeks and has eliminated 65 positions.

It has dug deeply into its investment fund, its capital base of bonds and other securities, thus undermining its financial foundation. The chamber's investment fund has declined from $19.5 million in 1980 to $14.3 million in 1981, based on the costs of the securities.

It spent most of that $5.1 million to buy property and equipment. But more than $900,000 of that capital went to pay for day-to-day operating expenses.

Another strategy has been a campaign to raise revenues by recruiting new members, who pay annual dues to the chamber. But that only has aggravated its immediate financial drain, according to the chamber's financial reports.

The chamber has sold memberships to subscribers of the Nation's Business magazine for a modest premium over the subscription rate. As a result, it now boasts that membership is up from 99,419 two years ago to 256,140 last month.

But it cost $4.9 million in commissions and other expenses in fiscal 1981 to raise $418,176 in added dues from the new members. Chamber executives said that the additional memberships will yield future profits from renewals because commissions to salesmen are paid only in the first year. A chamber source, however, said that internal computer studies are showing that only about 20 percent of these new members are currently renewing memberships.

The chamber is feeling the recession's impact in other ways. "We are taking longer to pay bills because our members are taking longer to pay us," says Lawrence B. Kraus, chamber vice president and general counsel. "We do not have debt. We are just taking longer to pay bills," he said.

A major expense to the chamber is the operation of the TV studio, which industry officials describe as perhaps the most advanced in the Washington area. Its centerpiece is BizNet, which beams five hours of business news a day to subscribers, who pay $5,000 a year for the service.

According to Milton E. Mitler, director of media relations, BizNet cost $350,000 since it started up in July. He says that BizNet's 1983 budget is $1.8 million and that he expects it to lose $400,000. Others at the chamber predict that the deficit could be much higher because thus far only a few local chambers and businesses have laid out the money for the necessary receiving dish and wiring.

But Carl Grant, group vice president for communications, says the big expense of BizNet will be justified. "We see it as the wave of the future. It gives us immediacy. It's the way we will communicate with our grass roots."

The chamber's current financial status isn't known because it has not released its annual report for the last fiscal year, which ended on June 30. Chamber officials say the report will be reviewed today by the board of directors.