One day, in the year before his death, Hubert H. Humphrey escorted me into his small, private Senate hideaway in the Capitol, closed the door and began a tape-recorded conversation that lasted several hours. The purpose was not social; I was gathering material for a book about the politics of Washington and the workings of government during the Carter years, and the former vice president was a prime source of information.

He was, of course, a great student -- and practitioner -- of government. When I asked what had been the greatest change since he came to the Congress, he instantly replied:

"Up until the time of Woodrow Wilson, with the exception of Teddy Roosevelt, we had congressional government. Congress was the predominating influence. That changed. The president became the predominating influence. Now Congress has asserted itself again. I can't overemphasize the importance of this. Congress is no longer afraid of the executive -- particularly when you look at things like the budget. I've heard dozens of people up here say, 'Well, I know that Carter's got that in his budget, but what's our budget say?'

"And I'll tell you something I hear people say now that you never heard before: 'I've seen them come and go, and I'm still here.' They're talking about presidents, you know. I've run through seven of them myself."

With that 1977 conversation in mind, I keep wondering how Humphrey would have reacted to the shameful political charade played out last week in Washington, by the very body of legislators that he so loved, the Senate. No one can know for sure, but my bet is he would have been saddened -- and outraged.

The overwhelming vote by the Senate to require a balanced budget by 1991 is more than abdication of responsibility and a sign of political failure on its part. It is a blank check for the president, signaling a dramatic reversal in the shift of powers back to the presidency from the Congress, a shift in the opposite direction from that hailed by Humphrey.

It's also a riveting example of the failure -- abject capitulation is a better term -- of the Democratic Party to offer a reasoned, responsible political alternative to the Reagan presidency and its tilted budget priorities that to a large extent got us into the present deficit debacle. They allowed themselves to be stampeded, and they ran.

As Sen. Bill Bradley (D-N.J.), one of the most thoughtful of the Democrats, put it last week in an article in The Washington Post, "this legislation shows Congress at its worst."

I believe Bradley's words, written on the eve of the vote, will stand out admirably after all the ducking and political posturing of last week have been forgotten.

"Instead of once again grappling on a bipartisan basis with the tough decisions, particularly on taxes," he said, "Congress appears poised in a moment of irrationality and timidity to give Ronald Reagan the sole power to reorder the priorities of the national government. It will be an action that we will all live to regret."

Behind this action lies a more significant political development: the ratification, if you will, of the Senate's willingness to place its powers and authority in the hands of the president because it lacks the will to act. By this action, Reagan has won. Much of the political history of relations between Congress and president that people such as Humphrey cited as important will have to be rewritten. It's quite recent history, too.

During the Vietnam-Watergate years, concern centered on the "imperial presidency" and the growing accumulation of power in the hands of the chief executive. Fears were expressed that a supine, deferential Congress was becoming a rubber stamp for the White House. But those also were the years in which Congress fought -- and won -- a battle to regain its lost powers.

The fight took two forms. In both foreign and domestic affairs Congress fought to limit the power of the president to act without its consent. In foreign affairs, congressional enactment of a War Powers Resolution in 1973 directly checked the president's power to act alone in involving the United States in armed conflicts It was the result of congressional determination to avoid further Vietnams. In domestic affairs, the establishment in 1974 of Congress's own budget office gave the legislators greater power over the purse. Until then, Congress had been a hostage of executive department proposals that shaped the federal budget. Through its own budget office, gathering its own information, Congress sought and did regain much of its authority over the dispensing of federal funds.

As House Speaker Thomas P. (Tip) O'Neill (D-Mass.) expressed the importance of that shift to me, during an interview several years ago in which he passionately pounded on his desk to make even stronger his point:

"The change in Congress had come. We had recaptured our powers to the extent that we were almost an equal voice. The press didn't read it. Jimmy Carter didn't read it. They didn't appreciate the power and the strength of the Congress of the United States. Jimmy Carter thought he was going to be another president with the powers of a Nixon or a Kennedy or a Johnson, and he didn't have 'em when he arrived here."

It is now left to O'Neill and other members of the House to save the Senate and the country from the damage that threatens to be done.