Secretary of State Alexander M. Haig Jr., calling reports that he had threatened to resign "a snake with legs on it," sought yesterday to put internal power struggles behind him and resume the task of American diplomacy.

"More than enough has been said" about the dispute over crisis management that ended with a major new assignment for Vice President Bush and an implied rebuke for Haig, the secretary of state told a crowded, klieg-lighted hearing on Capitol Hill. "From my point of view, I'm anxious to get on with the conduct of American foreign policy under the arrangements discussed yesterday by the president," Haig said in his first public reaction to the bureaucratic discord.

Before senators in the hearing room, Haig seemed notably less assertive and ebullient than in the past, omitting all reference to a role as "vicar" or "general manager" of foreign policy and depicting himself as a loyal member of a harmonious Reagan team.

In the corridor outside, where he briefly met the press, Haig was casual and flippant.

Referring to the widespread view that he had suffered such a serious personal defeat that he might be on the way out, he began by recalling the famous telegram of Mark Twain who, on reading his obituary in a newspaper in 1897, noted that "the reports of my death are greatly exaggerated."

Haig added, in a pun on the name of the victor in the bureaucratic struggle, that "somebody said I looked Bushed this morning."

Asked if he had threatened to resign, Haig answered: "You gentlemen are painting a snake with legs on it."

Later, he used the same figure of speech when asked if he felt his problems had been created or blown out of proportion by the press. Haig's office later explained that he meant "something that doesn't exist."

Haig told reporters that he had been informed by President Reagan after the decision that Bush would head crisis coordination. "There was some confusion with respect to what he [Reagan] thought I knew, and what I thought he knew -- but that's a minor matter," Haig said.

In his press appearance and in his testimony, Haig treated the disagreements about policy-making procedures and crisis coordination as questions of "form" with only secondary importance, compared to the "substance" of diplomatic positions.

"My concern is the substance and not the form of American foreign policy," Haig said. He added that he is "very comfortable" in this posture because "in substantive terms my views are very compatible with those of the president, if not identical."

Despite Haig's efforts to pass over the controversy brought on by his public expressions of dissatisfaction Tuesday morning, there was little doubt that his prestige and position have been seriously damaged.

Senate Majority Leader Howard H. Baker Jr. (R-Tenn.), in a breakfast meeting with reporters, said that after talking to Haig Wednesday afternoon "the impression I have is that he's going to stay for the time being . . . I can't see beyond that. Let me modify that and say I think he's going to stay."

Baker added: "It's a learning process, and I'm not greatly disturbed by what's happened."

House Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.), speaking to reporters, said it is just about an even-money bet who will resign first, Haig or Budget Director David A. Stockman. "The odds are 6 to 5 who goes first, who'll be around late in the fall," he said.

Rep. Benjamin S. Rosenthal (D-N.Y.), a member of the House Foreign Affairs Committee who publicly tangled with Haig a week ago in appealing for a more positive foreign policy, defended the secretary of state's position yesterday.

"The administration's idea that crisis management can be separated from day-to-day foreign policy is insupportable," said Rosenthal, who said Bush's appointment is "nothing more than an attempt to settle bureaucratic infighting." He added that the deeper issue is Reagan's leadership.

Substantively, Haig broke little fresh ground in his testimony to the Senate Appropriations subcommittee on foreign operations, a usually obscure legislative body whose small hearing room was suddenly invaded by scores of reporters and eight television cameras.

The secretary of state laid even heavier emphasis than ususal on Soviet "illegal interventionisms" and Soviet-Cuban activities as the source of world problems, and he declared more bluntly than ever that the United States will go to the "source" of disorder in El Salvador and Central America, meaning Cuba.

Haig defended the administration's proposal to sell F15 enhancement equipment to Saudi yarabia, and reported that the Carter administration had discussed with him a plan to take similar action in the period between last fall's election and Inauguration Day.

Haig said he felt the new administration should deal with the problem instead