In an indignant letter to the Speaker of the House, Rep. Henry B. Gonzalez (D-Tex.) submitted his resignation as chairman of the House Assassinations Committee yesterday after an admittedly futile effort to take charge of the inquiry.

He accused House leaders of failing to back him up in his struggle with the committee's chief counsel, Richard A. Sprague, and said that he saw no alternative to quitting "under the circumstances that now exist."

Accusing Sprague once again of mismanagement, insubordination and disloyalty, Gonzalez denounced him as "an unscrupulousindividual, an unconscionable scoundrel." Sprague, who has thus far had the backing of the rest of the 12 member committee, had to comment.

Apparently caught by surprise, House Majority Leader Jim Wright (D-Tex.) said he doubted the investigation would survive at all unless Gonzalez can be persuaded to change his mind.

The volatile Gonzalez phrased his resignation letter in terms that ostensibly made his departure immediate and final but, under a precedent established just two years ago, it is up to the House to accept or reject it.

Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.) said he would not schedule the issue for floor action until he first had a chance to speak to Gonzalez and try to dissuade him. Gonzalez has been bedridden with flu in his San Antonio home for the past 12 days.

O'Neill refused to speculate on what the House might do if Gonzalez remains adamant, but not a few members seemed agreed that it could well kill the entire investigation into the murders of President Kennedy and the Rev. Martin Luther King Jr.

Already reeling from the impact of earlier disputes over the inquiry's proposed cost and methods, culminating in Gonzalez' attempts to fire Sprague, the 12-member Assassinations Committee will go out of business March 31 unless it can get a new charter, and budget, from the house.

"In view of the low repute we have in the minds of other members of the House because of the unseemliness of the whole squabble, that might be hard to get," said Rep. John B. Anderson (R-III.), one of the committee's four GOP members. "The life of the committee still hangs by a slim thread."

The Speaker had already suggested, in a television appearance last week, that the committee would go out of business at the end of the month "unless they come up with something sensational," and he reiterated that judgment yesterday. He said some committee members had "told me they have some breakthrough on the King business," but O'Neill said he was not aware of what that might be.

Del. Walter E. Fauntroy (D-D.C.),who has been heading a subcommittee that would look intothe King assassination, hinted of a possible public hearing to "focus on the results of the investigation so far." But he declined to predict any bombshells, and other members said there was none to be produced.

The committee feels there's a good chance to crack the King case, but that's a long run," said Rep. Richardson Preyer (D-N.C.), the ranking democrat under Gonzalez. "But I don't know of any bombshells we're about to drop."

The committee was already prepared to postpone the investigation into President Kennedy's assassination, in anticipation of a much slimmer budget than the $6.5 million a year Sprague had proposed.

Appointed chairman just last month, Gonzalez said he was quitting in both chairman and as a member of the committee. He described the inquiry as mired down in "an administrative nightmare," and said he decided to fire Sprague only after finding "unjustifiable salaries, unjustified employees, and reckless, inexplicable financial obligations."

It seemed plain that Gonzalez would insist on Sprague's ouster if he were to be expected to change his mind. Alluding to an effort by a committee majority to secure paychecks for Sprague and the rest of the committee's 73-member staff in Gonzalez' absense, the chairman protested that some of his colleagues "appear to be interested in usurping even my ministerial powers."

"It seems clear now that the House leadership in unwilling to offer me support," Gonzalex wrote O'Neill. "Yet, I cannot bring myself to sign pay vouchers for an unscrupulous individual, an unconscionable scoundrel, and no power on earth can compel me to do so."

Gonzalez aides said he felt House leaders had expected him to bend too much in keeping Sprague on the committee staff. Majority Leader Wright acknowledged to reporters later in the day that he may have miscalculated on that score, thinking that Gonzalez could be persuaded to accept the prosecutor "in a reduced role."

Asked last month by Speaker O'Neill to mediate the dispute, Wright told reporters he had gotten the approval of eight of the committee's 12 members to a compromise he had proposed this week.

Wright refused to discuss the details, but it was learned later that it was a seven-point suggestion involving Sprague's retention as chief investigator and the hiring of "a new person acceptable to all the members" to replace Sprague as staff administrator. All "final decisions on hiring and firing would repose with the committee membership . . ."

O'Neill said House leaders would meet today with other members of the committee to discuss the dispute.