WASHINGTON -- From the outset, Paul E. Tsongas has faced a menu of unpleasant alternatives in making the decision he will announce at 10 o'clock this morning on whether to remain in the campaign for the Democratic presidential nomination.
The first question has been whether the former senator from Massachusetts had any realistic chance of accumulating the 2,145 delegates needed for a first-ballot nomination. And the answer, as Mr. Tsongas knew all along, is that he did not.
The second question was whether a reactivated Tsongas campaign could prevent Bill Clinton from reaching the 2,145-delegate level. And the answer has been that it was possible, although not likely.
So the fundamental question all along has been whether a renewed effort by Mr. Tsongas would accomplish any purpose worth the risks tohimself and to the Democratic Party. Judging by the absence of party leaders publicly urging Mr. Tsongas to continue, the answer to that one, among politicians at least, has been that the hazards are too great.
There has been no mystery about the arithmetic of the situation. Mr. Clinton now has the backing of about 1,300 of the 2,145 delegates needed to assure his nomination, the exact number being in some dispute because it depends how many of the so-called "superdelegates" consider themselves fully committed to the Arkansas governor. They are largely party officials and officeholders and officially unpledged.
There are still about 1,300 pledged delegates to be chosen in remaining primaries and caucuses. If Mr. Clinton could win half of them, he would be within 200 delegates of locking up the nomination, which presumably would come from the remaining pool of superdelegates.
That 50-percent share is obviously a higher proportion than he won in those Tuesday contests. But Mr. Clinton could benefit greatly from the fact that several of the remaining states -- North Carolina, Virginia and Alabama, for example -- are in the South and likely to give him a disproportionate share of their delegates.
Winning over those final 200 superdelegates may sound easier than it would prove to be.
In 1984, Walter F. Mondale spent four frantic hours rounding up the necessary handful of votes to meet a self-imposed deadline for "going over the top" -- a feat he managed with only eight votes and a few minutes to spare.
Thus, it remained possible to construct a situation in which Mr. Tsongas, by remaining active, would arrive at the convention with 1,000 delegates or so, twice his current holding, and try to block a Clinton majority by putting those together with the uncommitted or delegates elected under the banner of other defeated candidates, Sens. Tom Harkin of Iowa and Bob Kerrey of Nebraska.
The missing element in the calculations Mr. Tsongas and his advisers have been making since his surprise second-place showing in New York has been a scenario that could realistically be expected to produce a preferable alternative.
Among themselves, Democratic professionals have been talking about a scheme under which Mr. Tsongas would return to active campaigning but signal that his intention was to build a bloc of delegates for Sen. Lloyd Bentsen of Texas, the 1988 vice-presidential nominee and, at 71, enough of an elder statesman to be insulated from criticism for a late entry into the campaign.
There has even been some speculation about a package deal involving Mr. Tsongas as the vice-presidential running mate for Mr. Bentsen.
But the problem with that idea is, first, that any attempt to anoint a candidate would be sure to evoke a backlash among Democrats with different ideas about who should be anointed.