It is difficult to address George Bush as president, since he continues to conduct himself more like a vice president or a president-elect - going to funerals, revising his positions on issues, waving too much.

Yet, the judgment on the new president is too harsh. He is, in fact, the victim of two constitutional amendments, the effects of which are terribly underestimated.The first such hampering and damaging amendment is the 20th, which upon its adoption in February 1933 made Franklin D. Roosevelt the last president-elect to take the oath of office on March 4. Just what brought on this measure, known as the "lame duck" amendment, is unclear.

There was no record of obstructionism or irresponsibility on the part of Congress. Nor had a "lame duck" president abused the powers of his office. Moreover, presidents-elect expressed no serious frustration at being kept out of office for more than three months after their election.

The harmful consequences of changing the date are two. First, it obviously allows less time for organizing a new administration, making the inevitable "first 100 days" test unfair. Franklin Roosevelt's first 100 days did not begin until March 5, 1933, 116 days after his election. The starting point for George Bush's 100 days was Jan. 20, 72 days after he was elected. Roosevelt had a 44-day advantage.

The second serious consequence is that the president assumes office just before February begins, leaving him under pressure to make decisions in that month. Poets, philosophers and historians have had nothing good to say about February.

Even animals shun decisions in February. Bodily and mental functions among the higher order mammals are at their lowest level of the year. Only the groundhog, by reputation, breaks the pattern and then only for a quick look for his shadow.

The amendment that adversely affected the Bush transition is the 22nd, initiated in the 80th Congress and ratified in 1951, which limits presidents to two terms in office. The amendment was adopted as a way of getting back at Franklin Roosevelt after he had died. The current evidence is that the amendment has served no national good.

It has most decidedly complicated the Bush assumption of power. If the two-term limit had not been in place, then the incumbent would either have refused to run for re-election or been rejected by his own party as a nominee. Either way, his successor would be left relatively free of obligation to or dependence on his predecessor.

As it now stands, President Bush must cope with the lingering doubt that, barring the 22nd Amendment, Ronald Reagan would have run successfully for a third term. Bush is thus caught between continuing as a kind of stand-in for Reagan and breaking with the Reagan lines and appearing either as ungrateful or as seeking without good reason to prove that he is his own person.

As a part of proving the latter, he must put his own people in place. In this process, the Reagan Cabinet members identified with desirable policies, such as George Shultz as secretary of state, absolutely have to go. Others identified with less than successful policies can be replaced with new Cabinet members whose only recommendation is that they are new, not different.

The defensive reaction is likely to be that which Bush is now demonstrating: hedging on policies, appointing persons of no strong commitment and shifting personnel from the old administration to different posts in the new until the final team emerges.

Before we compare the Bush transition and Roosevelt's 100 days, we should at least give Bush 100 days after March 4.

(Eugene J. McCarthy, a Democrat, is a former senator from Minnesota.)