In an official response to President Reagan's nationally televised speech Wednesday night, Democrats yesterday accused Reagan of presenting a distorted and misleading account of the U.S.-Soviet balance of power in order to protect his "excessive defense budget" and "divert our attention from the dismal failure of his economic policies."

Congressional Democrats chose Sen. Daniel K. Inouye of Hawaii to deliver the party's rebuttal.

At the same time, a number of other Democrats, some liberal Republicans and a Nobel Prize-winning scientist also criticized Reagan's call in his speech for an all-out research effort to see if a high technology defense against missile attack can be developed in the next two decades.

The Democratic charges escalated the widening battle between the administration and its critics over the size of the defense budget, nuclear policy and the best way to preserve national security.

At the White House yesterday, administration officials reinforced Reagan's position that it was his duty to tell the public about the Soviet threat and what the United States must do to meet it, while on Capitol Hill there was a growing consensus that the Reagan defense budget was too big and would be cut.

Senate Majority Leader Howard H. Baker Jr. (R-Tenn.) and Minority Leader Robert C. Byrd (D-W.Va.) said they believe the Senate will approve a defense budget somewhat higher than the one passed by the House Wednesday but far short of the administration request for a 10.3 percent increase, after inflation. House Minority Leader Robert H. Michel (R-Ill.) said he doubted that an eventual House-Senate compromise will include an increase of more than 6 percent.

The current House version allows for a 4 percent increase.

In the Democratic policy rebuttal to Reagan's speech, Inouye said, "The president attempted to instill fear in the hearts of the American people, to raise the specter of a Soviet armed nuclear attack.

"He left the impression," Inouye continued, "that the United States had stood still while the Soviets had accelerated and vastly expanded their nuclear arsenal . . . that the United States is at the mercy of the Soviet Union. Mr. President, you know that is not true. You have failed to present an honest picture."

He said Reagan failed to point out that Soviet land-based missile strengths are "more than offset" by U.S. atomic warheads on missile-firing submarines and bombers. He said the total of such atomic weapons showed 7,339 for the Soviets and 9,268 for this country.

The administration claims that the Soviet land-based missile edge gives them a theoretical first-strike threat against U.S. missiles.

Sen. Sam Nunn (D-Ga.), an influential member of the Senate Armed Services Committee, said in an NBC-TV appearance that the Soviet threat "is real. There is no doubt about that." But he also said, "I would fault the president's speech for not taking into account America's strengths, the strengths of our allies and the weaknesses of the Soviet Union."

Inouye, a member of the Senate Intelligence Committee, said he deplored the selective declassification of intelligence photos used by Reagan Wednesday night to show military installations in Cuba and Nicaragua.

Inouye asked why Reagan chose to highlight the basing of Soviet-built MiG jet fighters in Cuba at this time, when they have been there for years. "Why did he suggest American inferiority. I believe he did so because he is afraid his excessive defense budget will be trimmed by the Congress and because he wants to take our attention off the economic disasters brought on by his policies," Inouye charged.

The big surprise in Reagan's speech, however, was his placing a top national priority on attempting to develop a workable defense against intercontinental ballistic missiles. The president suggested that success in such an endeavor could lead eventually to a dramatic shift in strategy away from reliance on quick nuclear retaliation as the only way to deter attack.

Senior administration officials yesterday portrayed Reagan's emphasis on defensive weapons as "a deep commitment . . . to get off this trail, this interminable route of buildup of offensive nuclear weapons."

But Sen. Mark O. Hatfield (R-Ore.) said, "This is not, as the president suggests, a shifting of our national genius away from war. It is a call to siphon off the meager and inadequate commitment which now exists to rebuild America."

Hatfield, chairman of the Senate Appropriations Committee, said, "The president's advisers must be called to account for these terrifying proposals." Reagan, he said, "has, in effect, called for the militarization of the last great hope for international cooperation and peace--outer space."

Although the administration says it wants to explore many new technologies, there is special interest in exploring lasers and other weapons using highly focused beams of energy as possible space-based interceptors.

These weapons could aim their rays at enemy missiles soon after they were launched and shoot them down before they had a chance to dispense atomic warheads. Administration officials stress, however, that they are also interested in ground-based systems.

In Spain yesterday, Defense Secretary Caspar W. Weinberger said the kind of research and development program called for by Reagan would be "fully consistent with the treaty," Washington Post staff writer George C. Wilson reported, because "the treaty goes only to block deployment." Weinberger pointed out that the president had committed himself only to study the technology, not to deployment.

But Jeremy Stone of the Federation of American Scientists pointed out that the 1972 treaty does ban development and testing, as well as deployment, of "ABM systems or components which are sea-based, air-based, space-based or mobile land-based."

Administration officials said yesterday that it probably would be another five or 10 years as the research progresses before the president's plan could come into conflict with the treaty and that provides "ample time to discuss this with the Soviets."

Successive administrations have invested billions in ABM research for some 20 years. But no system has proved workable and it has always been reasoned that such defenses could be thwarted by countermeasures or overwhelmed by an enemy who just adds more warheads.

In recent years, however, new technologies have progressed to the point where they may offer some advances for anti-missile work. Weinberger and other officials yesterday acknowledged that while the quest for an answer is old, what is new about the president's action is that he has elevated the goal to a national priority and thus given the program a better chance to succeed.

Many critics, however, argue that the search for an ABM will induce a false sense of security and that this could destabilize the nuclear balance because one side may feel it can launch an attack and safely shoot down the other side's retaliatory force.

In a telephone interview yesterday, Hans Bethe, the Nobel Prize-winning nuclear physicist who was one of 13 scientists invited by Reagan to attend a White House briefing Wednesday, said he was "worried" by the development and that he got no answers when he asked about this potential for destabilization.

Bethe said about the ABM challenge: "I don't think it can be done" and questioned why Reagan announced his plan now when the president acknowledged it might be the next century before such a system could be deployed.

"It will cause a race" between the United States and Soviet Union, Bethe predicted, "but what is worse is that it will produce a star war, if successful," in which each side also will race to develop better anti-satellite weapons.

This, he believes, will inevitably lead to U.S. intelligence-gathering satellites becoming vulnerable to attack. "So we will lose our eyes" and in a crisis or war "we won't know anything."

Administration officials said yesterday they did not know how much more the president's plan would cost beyond the $1 billion annually already spent on such research.

There was also uncertainty yesterday about how the president came to his decision to propose this plan. Officials said that the president's decision was "triggered" during a routine meeting with the Joint Chiefs of Staff six weeks ago. Officials declined to say, however, what it was that the chiefs said that triggered Reagan to act on his supposedly long-held views about the benefits of missile defense.

One source said that at the meeting the chiefs expressed concern about preliminary conclusions of a special commission studying overall U.S. strategic forces, including the MX missile.

Both the chiefs and the commission reportedly believe that retaliatory forces were becoming increasingly vulnerable and that some new effort would have to be made to try to maintain deterrence.