Gerald P. Carmen, who has been selected to oversee the sale of billions of dollars in property from failed savings and loans, came under attack yesterday by House Democrats who cited his record at the General Services Administration, where he hired relatives and political cronies and appointed an official later convicted of bank fraud.

Carmen, who ran President Reagan's 1980 campaign in New Hampshire, also raised some lawmakers' eyebrows yesterday by disclosing that a top lobbyist for the S&L industry introduced him to directors of the Federal Asset Disposition Association, or FADA, who were looking for a chairman.

At the urging of the industry, FADA was created by the Federal Home Loan Bank Board, which regulates savings and loans, to manage and sell the growing collection of property the government is inheriting from failed S&Ls.

FADA, which has lost $15 million since it was formed, has been plagued with charges of conflict of interest, favoritism and mismanagement. Carmen would replace Roslyn Payne, who was forced out as FADA's chairman last fall. Payne remains as president of FADA and retains her $250,000-a-year salary, which makes her the highest paid government appointee.

The disclosure of the role of a top lobbyist for the U.S. League of Savings Institutions, Richard F. Hohlt, in the selection of Carmen comes as critics in Congress and the financial community are blaming the mounting problems of fraud and mismanagement in the S&L industry in part on the cozy relationship the industry has enjoyed with bank board officials who regulate it.

In a letter to the bank board yesterday, House Banking Committee Chairman Fernand J. St Germain and three other members of the panel questioned Carmen's qualifications to head FADA. The letter was sent to bank board chairman M. Danny Wall, who has said he is a longtime friend of lobbyist Hohlt.

Asked about the Hohlt's role in introducing Carmen to FADA, Wall said, "It doesn't make any difference who makes the introduction if the person is qualified." Hohlt could not be reached for comment.

"Everything in the letter is old news," Carmen said in an interview. "Each allegation has been fully investigated by appropriate committees of the Senate and I've passed two Senate confirmations.

"I've a seen a copy of the letter and I liked it so much I've decided to take the job," Carmen said. Earlier in the day he said he had not made a final decision.

The letter from House Democrats represents the latest rebuke of FADA by lawmakers. St Germain's staff is putting the final touches on a report on FADA that will call for radical restructuring and possibly the abolition of the organization. The report is expected to be issued within two weeks.

The letter cited congressional hearings in 1982 where lawmakers "raised serious questions" about how Carmen sold some properties when he headed GSA from 1981 to 1985.

When he left GSA, Carmen became ambassador to the United Nations European mission in Geneva. He ran Laxalt's brief entry into the presidential race last year and now works with his son's political consulting and public relations firm in the District.

The letter from Congress also cited newspaper stories from 1982 that said Carmen created more than 35 political patronage jobs with salaries totaling $1.5 million from 1981 to 1985. The reports said the "beneficiaries of these high paying jobs included his daughter and her boyfriend, political cronies, and former employees of his automotive business in New Hampshire," the letter said.

In the interview, Carmen responded to the charges by saying, "Sure I hired people I had confidence in and who I knew. As far as cronyism is concerned, maybe {Congress} ought to take a good look at itself."

The letter cited Carmen's appointment of Donald Ellison as administrator of GSA's Boston regional office, his indictment four months later and his guilty plea to embezzlement and defrauding a bank.

Carmen acknowledged the incident but said he had relied on Ellison's references. "The record speaks for itself. The newspaper clips speak for themselves," he said, adding that they would confirm his claim that he generally received high marks for his tenure at GSA. "This is a story of Democrats going after Republicans, isn't it?" he said.