A run for the White House is the headiest of highs in political life. A national campaign, introductions as ''presidential candidate,'' even the ignominy of polls that find barely a trace of public support - all can contribute to an effort that is pure politics; that is, apart from candidate desire, devoid of the clear urgency in issues or a strong public will that lends a candidacy significance.
This burden - a candidacy apparently in search of a coherent political commitment - is the challenge faced by John Anderson's anticipated second White House bid in 1984.
The party Mr. Anderson intends to form, tentatively called the National Unity Party, itself is a creation of political convenience. To qualify for some $5.8 million in federal election funds that his 1980 showing made him eligible for, Anderson must be nominated by a party. The party itself must qualify by gaining enough voter signatures to put it on the ballot in 10 states.
By becoming the candidate of a third party, Mr. Anderson sacrifices much of the independent gadfly elan that became known as ''the Anderson difference'' in 1980, which for a time infused the general campaign with a welcome verve.
Many of Anderson's former aides have urged him not to run. A formal party structure will only make him into even more of the conventional candidate than he had become as the 1980 race wore on, they argue.
History offers a third party little hope of success on its own in 1984. Usually third parties fare well when there is deep dissatisfaction with the two major parties. For some time now voters have been reverting to their basic Democratic and Republican allegiances, not abandoning them. In 1980, Anderson's early popularity stemmed from voter dissatisfaction with the major candidates, not so much with their parties. No such aversion is apparent now.
This offers an Anderson party little room for maneuver. Anderson himself talks of its taking several elections for a new party to establish itself.
We'll see. One of the grand things about the American political system is that anyone who can qualify for the White House, by nationality and age and meeting Federal Election Commission rules, can try for it.
Anderson so far has been striking liberal poses. He's called for a nuclear freeze, defense cuts, a ''global Marshall Plan'' to help the third world, federal aid to education, women in the Oval Office. He hopes to target Reagan ''deficit spending'' to attract conventional GOP support.
Surveys show Anderson pulling about half the public backing of his previous run (12 percent to 15 percent compared with a high of 24 percent in 1980). His support dwindled steadily until on election day he won 6.7 percent of the popular vote. The same pattern is anticipated in 1984.
In a close race, however, which seems likely, even a slim slice of votes for Anderson could prove significant. By about 4 to 1, Anderson's strength seems to be coming from the Democratic column, giving Reagan even more of an advantage than he already holds in states like California.
Of course, it is up to Mr. Anderson to make his campaign into something more than an ego trip or a spoiler's run. The federal cash looks enticing - close to still have to raise another $34 million from regular contributors to match the $ 40 million the other candidates will be allowed to spend.
Whether he will be invited into a presidential debate next fall will depend on whether the major party candidates will find it to their advantage to play up his candidacy.
Anderson's weight in the balance of power, not his ideas or contribution to the larger debate, seem destined to win him attention in '84. This should disappoint him. Or spur him to prove the expectations wrong.