The drive for a federal consumer protection agency, warmly endorsed by President Carter and widely regarded less than a month ago as an easy victory for him, is suddenly in trouble.

Intensive lobbying by business interests has marshaled enough opposition to the measure to make it too close to call when the bill comes up for a vote today in the House Government Operations Committee.

Countering the business pressures has been an all-out campaign by organized labor and the White House, culminating yesterday in personal letters from Carter to most committee members and the phone calls from Vice President Mondale "to some of the Democrats who've been on the fence."

"It's within three votes either way," said Rep. Benjamin S. Rosenthal (D-N.Y.), the chief House sponsor of the bill. "All the silk stocking lobbyists in town are opposed to it. They even went out and bought [former Watergate prosecutor] Leon Jaworski. He wrote a letter to all members of the committee, raising the specter of unconstitutionality."

Retained by the Business Roundtable, a high-power association of more than 100 of the nation's biggest corporations, Jaworski wrote a letter to all House committee members April 27 assailing the proposed "Agency for Consumer Advocacy" in terms very much like those critics used to raise about Jawoski's on Watergate prosecution force.

The new agency, headed by a presidentially appointed administrator, would be empowered to represent consumer interests before other federal agencies and to file court suits to challenge adverse decisions.

Declaring that he and his Houston law firm have been working voluntarily with "other members of the business community in an attempt to demonstrate why the consumer protection agency concept should be abandoned," Jaworski maintained it would have too much power.

The new agency "would be vested with authority so broad that it could easily be turned to the political advantage of those who control it," the former Watergate prosecutor protested in his letter. "There are no checks suggicient to harness that authority. Under these circumstances, creation of the new agency is unwise.

According to Rosenthal and other supporters of the bill, the chief strateoist against the measure has been former Republican White House aide Bryce Harlol on behalf of the business Roundtable and his own firm, Procter & Gemble, with support from the U.S. Chamber of Commerce, the National Association of Manufacturers, and the Grocery Manufacturers, and the Grocery Manufacturers of America, among others.

Harlow said he supposed he should be flattered by the designation, but insisted there was no real "chief strategist" for the opposition. He said the same companies and associations have been fighting the measure for eight hears now and "the nexus nor it all" was not him, but Emmett Hines, Washington representative for Armstrong Cok.

Slightly different versions of the bill were passed by both the Senate nd House in 1975, but the measure was never ent to the gwitt House because of a promised veto by President Ford. Carter made it a major campaign issue laet September and called for creation of the agency in a special message to Congress last month.

The lobbying became intense after a quick set of House subcommittee hearings last month, according to White House assistant for consumer affairs Esther Peterson. One General Motors lobbyist, she said, kept coming up and telling her, "Esther, I've got 21 votes already. Why don't you give up?"

The committee has 43 members, 29 Democrats and 14 Republicans. By all accounts, organized labor, led by Evelyn Dubrow of the international Ladies Garment Workers Union, the United Steelworkers and the United Auto Workers, got busy last week.

Finally appreciative of the crisis, the White House stepped up its efforts over the weekend.

Labor leaders, meanwhile, began trying to counter the hometown calls the Chamber of Commerce had generated against the bill.

"It's been a very effective effort, on both sides," said Rep. Floyd Fithian (D-Ind.) who said he planned to vote against the bill. "At first the chamber and their allies had it all their way, but in the last week or so, organized labor has been coming to life as it never did on the situs picketing bill. The chamber's been lobbying in a very sophisticated way; they've been checking around in my home district and finding out who's really on good terms with me and asking them to make the call."

As for the organized labor effort, Fithian added last evening. "I've got to call the UAW president in my hometown right now."