Summer belongs to Congress in Washington. This may be true of some other special times, such as that couple of weeks before Christmas when the power plays and deadline bartering and general collapse of dignity combine to create an annual entertainment that is as much a part of the holiday season as "Peter and the Wolf." But it is somehow in the lore and each legislator's biologic clock that the steamy days of summer in Washington shall be (even the classic movie image of the raucous, sweat-soaked filibuster affirms this) the time of congressional pre-eminence.

This year is no exception. The Hill is becoming the locus of all the most interesting things that are going on. But that are going on. But that is not, I think, just a consequence of the predictable tension between Washington's vestigial Democrats and its newly installed Republican administration. The big question, it seems to me, the one that is lurking behind all the conflict -- whether it involves Jesse Helms or Ernest Lefever or Tip O'Neill or Dan Rostenkowski or Charles Percy -- is what, if any, role the political culture thinks it suitable and/or safe for Congress to play.

We have just come through a decade or so of tedious and ponderous attention to this subject, replete with all those extreme statements people like to make when a fashionable idea overwhelms them. So the '70s were a time of struck poses concerning the God-given right -- not to say the sacred duty -- of legislators to intervene in everything. Now no one seems so sure. I even discern an occassional whisper in the air that is not quite right for Congress to do anything to thwart the will of the new president.

I'm thinking here of something quite apart from purely tactical considerations which the Democrats are debating with their usual lack of discretion: is it or isn't it political suicide to be seem to be opposing Reagan (never mind the merits) at the moment? For it's not just politics, but also institutional entitlement that you find people worrying about.

Consider Jesse Helms. My view of his terrorizing of the administration on some good and important appointments to the State Department is that it is (1) unfortunate and (2) unnecessary for the administration to sustain, since the president, at least at the outset, had much more power than he exercised in this relationship. He could have told Helms where to get off -- perhaps still can and will. But to say, as some do, that Helms as a senator has no business interfering in the administration's internal affairs is something else again.

Still, that seems to be the growing sentiment, rather than the view that Helms simply speaks for a lot of truly terrible ideas. And, from the other end of the Republican Senate spectrum, resistance to Reagan's wishes is viewed by some similarly. It was no secret inside the Washington Beltway before Lefever withdrew that there were plenty of Republican senators who believed him a very bad choice for the human-rights job at State and yet who would have voted for him. The theory here, as well, was that you can carry all this advising and consenting too far, that a president, unless he tries to make Fidel Castro head of the CIA, is entitled to just about anyone he wants and that senators of his own party have a moral obligation to vote accordingly. That is why Sen. Percy's stubborn rebellion was so notable and, in my view, admirable.

Yes, there have been huge breaches of this protocol in the past. One thinks of Senate Republican Leader William F. Knowland during the Eisenhower years and of Senate Democratic Leader Mansfield and his many fractious and unhappy colleagues under LBJ. But the big talk about congressional prerogatives and checks and balances and the rest that ballooned up over the Capitol in those years has been muted. Right now the word is that your are a Republican or a Democrat, a conservative or a liberal and, above all, a would-be political survivor; and this collection of attributes, not some dim sense of independent calling as a legislator, is what is meant (and expected) to guide your actions.

All this -- Congress's sense of itself -- is about to be put to a fascinating test. The context will be the coming phase of the budget struggle. It might have occurred under any president who held office this year, since Congress last year strengthened its own budget-approving procedures to make the discipline it was newly imposing upon itself even tighter. But the central importance of the federal budget to reagan's whole purpose in office and the enormous changes he is trying to make in spending trends sharpens the challenge considerably. The question is whether Congress can function responsibly as a budget-making entity except by yielding up most of its authority to the executive branch.

Until just a few years ago the question was irrelevant because Congress hadn't even attempted to produce a whole, i.e. responsible, budget -- it just authorized and appropriated what it pleased without thinking in terms of limiting this to pay for that and so forth. The budget reforms of the 1970s changed that. But this year things have been so tightened up and schedules so rearranged that the next series of budget votes could go one of two ways: they could amount to an enforced acceptance by committee chairmen of the wishes and will of the administration and of the resolutions Congress itself has earlier passed -- or they could amount to a busting wide open of the discipline and reform, a reversion to type whereby each committee does "its thing" and the unified budget goes out of the window.

I get a sense from the Hill now of one of those classic institutional turning-point battles -- the barons against the prince, the counties against the central government. How much will they give over to orderly, modern, managerial-type governing? Will they give over everything, including not just their clout but also their political predilections? Not likely -- but can they reclaim a proper amount of say-so without becoming, budgetarily speaking, just another rogue legislature? Disregard all that hairsplitting accountancy argument. Watch whether your friendly legislators are able to assert their influence without wrecking the reform of their system so far. You are about to see something important happen.