THAT witty newsman, Mark Shields, put the question to the President the other morning in his usual bantering way: ``Mr. President, after the death of the President for whom you four times voted, a group of petty, vindictive men who could not defeat Franklin Roosevelt during his life sought to get even with him in death by passing the 22nd Amendment to the Constitution, limiting presidents to two terms. Thus, you can never run again. How do you feel right now about the 22nd Amendment, and do you see any circumstances under which you would advocate its repeal?''
The President: ``Yes.''
This prompted a burst of laughter from the journalists assembled for the questioning session.
The President continued after a pause: ``But let's make one thing plain: I would not be talking about myself. No one could ever take on that problem while in office and without ruling it out that he would run again, and ruling that any change would have to be implemented for the next person that holds the office.''
Mr. Reagan said he had changed his mind on the two-term issue since becoming President. ``But since I've been here,'' he went on, ``I've come to feel, and not for myself, that this is an infringement on the people's democratic rights. We have congressmen and senators who serve up to 40 years and are elected time after time. Why do we say to the people of this country that they cannot choose who they want for as long as they want him in this particular office. There are plenty of safeguards against the power of the presidency that would prevent him from becoming a lifetime monarch or the like. But I now think that the people should have the right to vote for whomever they wanted for as long as they wanted.''
Now, here was a chief executive who, despite being the oldest person to hold the presidency, had not become tired and ready for retirement. He shows as much vigor and enthusiasm as when he moved into the White House.
Were it not for the two-term limitation, Reagan would be a likely candidate for another term. Because of some physical problems he has had, he might think it best to step aside. But no one could rule out the possibility that Reagan could, if not restricted by the Constitution, seek another four years -- in the hope that he could further reshape the federal government in line with his conservative point of view.
If a change in this two-term limit is to be made, it should get under way soon, during Reagan's final three years. The next elected president might not want the restriction to be dropped.
About here, a supporter of the two-term limit is likely to say something like this: ``How about the two-term tradition set by George Washington? I think it is a good thing and should continue.''
Mr. Reagan dealt with this question. ``I grew up,'' he said, ``in a country with that tradition that Washington set. I accepted that. But he set the tradition about two terms because at that time everyone was very conscien-tiously watching to make sure that we not become anything like a kingdom -- that we not begin to have inherited positions and so forth.''
But Reagan added that the election of Franklin Roosevelt to a third and fourth term had ``proved'' that this could happen without ``impairing'' the democracy. Thus, he emphasized, the real impairment to democracy now came from the voters' inability to keep a president in office as long as they desired.
It is ironic that the Republicans, who were the leaders in limiting the president's tenure, have been the principal sufferers, politically, from the amendment. Dwight Eisenhower very likely would have been elected to another term. And Reagan would probably prove a winner once again. On the other hand, the Democrats who came in after Roosevelt -- Truman, Kennedy, Johnson, and Carter -- never reached the position where they were restricted by the rule.
The two-term limit tends to make a president a lame duck and relatively ineffective by the midpoint of his second term -- and sometimes immediately after reelection. This hasn't happened to Reagan yet, but it could in another year.
A number of political scientists, members of Congress, and political leaders are advocating a one-term, six-year presidency. This idea might work out better than the present two-term limit. On the face of it, it would guarantee a president six years, as opposed to four, to get his job done. But it might also mean that such a president would become a lame duck shortly after getting elected, perhaps after just one effective try at getting his program through Congress.
Mr. Reagan's change of heart on limiting a president's time in office is based on his experience. His argument is persuasive.
If he decides to push ahead on this, he conceivably could, with his popularity, get the amendment changed for his successors.
Godfrey Sperling Jr. is the Monitor's senior Washington columnist.