The Senate confirmed Paul C. Warnke yesterday, 58 to 40, as President Carter's chief negotiator in strategic arms talks with the Soviet Union.

Warnke also was confirmed, 70 to 29, as director of the Arms Control and Disarmament Agency.

The votes followed four days of angry debate. Critics, led by Henry M. Jackson (D-Wash.), said Warnke had suddenly altered his previous "soft" views on the nuclear balance and on U.S. weapons needs only after being nominated and only in order to win confirmation. They said they wanted a negotiator whose views were more firm, tough and consistent.

Jackson also charged that Warnke had "doctored" a 1972 statement, when presenting it in 1977, to give the false impression he had been tougher than he actually was on the question of holding down any numerical Russian lead in strategic weapons. In his summing up, Jackson said Warnke has always been "indifferent" to the dangers of a possible big Russian numerical lead because he believes "an imbalance is meaningless."

Warnke defenders, led by Hubert H. Humphrey (D-Minn.) and George McGovern (D-S.D.), denied Warnke had been "soft" and said statements made in an entirely different arms era had been wrenched out of context by some critics and used against him."What he said in 1972 was based on the outlook in 1972," said Humphrey. He said Warnke is fully aware of possible dangers from any numerical Russian lead.

In the larger sense, the big vote against Warnke as negotiator reflected fears on the part of many senators that Warnke might give away too much to the Russians and place the United States at a strategic disadvantage.

In effect, the substantial vote against him constituted a "signal," as opponent Sen. Howard H. Baker Jr. (R-Tenn.), the GOP leader put it yesterday, that he should take a firm, strong position and bring back an arms limit treaty that would be fully equal and fully acceptable.

A treaty would require a two-thirds Senate vote for approval. Jackson and others worked hard to hold the negotiator confirmation vote below two-thirds to demonstrate to Carter and Warnke that they would be able to black any treaty that doesn't measure up to their views.

"All this is a dress rehearsal," said Humphrey. "They're hopeful they're sending a message to the administration on the kind of treaty they expect."

A few hours before the votes, President Carter, in his nationally televised news conference, told the nation "I have complete confidence" in Warnke. He said everything finally agreed on with the Russians "will have to be approved by me." Carter said he wants "a susbtantial reduction" in nuclear weapons to be negotiated, and that he thought many of those opposing Warnke "just don't want to see substantial reductions in nuclear weapons."

He said he didn't believe "the exact vote would "have a major effect on future negotiations" except, he implied, to the extent that a really low vote might be construed as "a demonstration of lack of confidence in my own ability" as ultimate director of the negotiations.

Both Baker and GOP assistant leader Ted Stevens (R-Alaska) said later that they favor arms control, would support efforts, once negotiations start, to reach a satisfactory treaty, but were voting against Warnke for negotiator because they simply didn't think he was the right man for the job.

Sen. John G. Tower (R-Tex.), another opponent, said he resents implications "that those who oppose the nomination are mindless warhawks who are prepared to see the world destroyed in a nuclear holacaust."

One Pro-Warnke senator who skipped the vote yesterday, Birch Bayh (D-Ind.), went to California because, aides said, he was certain there were enough votes present to confirm the nominee. Bayh was scheduled to make two appearances before United Jewish Appeal groups, for honorariums of $2,000 each, and to participate in a Dinah Shore TV program on the Equal Rights Amendment.

Before the Armed Services Committee held its hearings on Warnke two weeks ago, pro-Warnke vote counters were confident they had two thirds of the Senate on their side.

The Emergency Coalition Against Unilateral Disarmament and several other "hardline" organizations waged a massive mail campaign against Warnke which some senators said privately had pushed several undecided senators into the "no" column.

On the more controversial 58 to 40 vote on the negotiator post, both Maryland senators voted for Warnke, both Virginians against.