King Hussein of Jordan yesterday defended his Middle East peace initiative and request for new U.S. arms, telling two groups of congressmen that his kingdom now recognizes the right of Israel to exist.

The king met with House and Senate members at the start of a heated debate in Congress over the administration's request to sell up to $1.9 billion in arms to Jordan. One key senator warned that unless Hussein makes "significant movement" toward entering direct talks with Israel "in the next 50 days" there is little likelihood the request will be approved.

The king met first with 50 to 60 House members and then with 35 senators in an effort to convince a skeptical Congress of his willingness for talks with Israel. Vice President Bush also attended the Senate session.

Sen. Richard G. Lugar (R-Ind.), chairman of the Senate Foreign Relations Committee, said the king had declared the state of belligerency between Jordan and Israel to be over. The senator described the session as "very productive" and praised the king's defense of his views as "very helpful."

A more negative view of Hussein's performance came from Rep. Lawrence J. Smith (D-Fla.), who said he had heard "nothing new" and that the king continued to insist on holding direct talks under the umbrella of a United Nations-sponsored international conference, which would include the Soviet Union. Both the United States and Israel have rejected such a forum.

"I didn't feel he left any room for movement," Smith remarked.

Smith was the sponsor of an amendment to the foreign aid authorization bill barring any sale of advanced U.S. weapons to Jordan unless the king is publicly committed to recognizing Israel and to negotiating "promptly and directly" with the Jewish state.

Yesterday, Smith said he planned to introduce a new resolution in the House disapproving of the administration's proposed arms sale.

At a breakfast meeting with reporters yesterday, Lugar warned that "the most important factor" in Jordan meeting congressional conditions before an arms sale would be "to see the parties negotiating and seeing some results."

Without some movement toward this end within the next 50 days Congress has to consider the administration's arms request, he predicted congressional approval of the arms sale would be "difficult."

Lugar has been urging senators to "keep the powder dry," as one staff aide put it, on their opposition to the arms sale until it is clearer whether some progress can be made toward starting direct talks between Jordan and Israel.

Meanwhile, two other senators, Daniel K. Inouye (D-Hawaii), and Robert W. Kasten Jr. (R-Wis.), wrote letters to Secretary of State George P. Shultz charging that he had failed to fulfill a promise made in a June 20 letter that the administration would engage in "broad-based and constructive consultations" with the Senate before sending its arms request for Jordan.

"Frankly, Mr. Secretary, I believe you have broken your word to us," Kasten wrote in a Sept. 30 letter to Shultz. "Neither I, nor Sen. Inouye, who also was given your personal assurance of prior consultation, has been so consulted by you or any other official of this administration."