FOR A president and a Congress who have been chronically unable to get along, the last few weeks of budgetary negotiations have had an unaccustomed air of cooperation and shared determination to them. The president's proposed changes are very similar to those already decided upon by the House Budget Committee, and the tenor of the White House announcement has been to emphasize the areas of agreement -- not the differences. With luck this financial Camp David may last through the grueling rounds of further negotiations that must precede a 1981 budget balance.

The list of cuts has two distinguishing characteristics: it is a generally fair spreading of the pain in the short run (though each of us could quibble with some bits of it) -- but short run is the key phrase. Putting off initiatives, freezing numbers of employees and lowering program levels here and there across the government will buy some time for major reworking of the way the government does business. But that is all. In any given year, little more than that can be managed, because over thre-fourths of federal expenditures every year go out automatically. In 1981, some $470 billion will flow into and out of the Treasury untouched by human hands, a result either of statutory entitlements or of contracts from earlier years.

Therefore, the more difficult test of this new political determination will come in the follow-through, the ability, if it's there, to pull back from the "entitlement ethic" that asserts eternal rights to program benefits once they have been enacted, and which has for years required that changes in benefit programs be made only in the upward direction. The agreed-upon list of cuts includes a few not-too controversial changes in entitlements -- moving from semi-annual to annual indexing of federal pensions and food stamps, for example -- to bring those programs into line with such indexed behemoths as Social Security.

These changes, and the larger ones that will have to be dealt with soon, will require particpation of a much broader array of members of Congress, in particular the Ways and Means and Finance Committee chairmen who oversee the vast preponderance of entitlement programs. Holding a steady course is never an easy job for a politician; asking a large group of politicians to do so through the vagaries of an election year may seem mad. But that is just what the electorate seems to be asking of this president and this Congress. The question is whether they can -- and will -- continue the work that they have started.