Boston — For John Anderson, the magic figure in the next few weeks is 15 percent. Clearly needed, as Anderson strategists see it, is much more exposure designed to bring the candidate to that level of support in the major public opinion pools so he can share the platform with President Carter and Ronald Reagan in the series of televised debates sponsored by the League of Women Voters beginning Sept. 7.
Participation in the debats is a virtual must for the independent presidential candidate if he is to convince voters that his candidacy is a viable alternative to those of the Democratic and Republican nominees.
At present, the candidate stands at 14 percent in the latest Gallup poll. The Gallup, Harris, Roper, Associated Press/NBC, CBS/New York Times, and Time/Yankelovich organizations will sample public opinion on the matter again during the final week in August.
Now that the Republican and Democratic national conventions are no longer center-stage, Mr. Anderson begins what could be a crucial four-day, four-state foray into New England, where his candidacy has had particular appeal.
Noting their candidate's dip in some of the polls after the Republican convention in July, Anderson lieutenants are anxious to prevent further slippage at this time, when he has so much at stake in his independent bid, a route on which all previous political travelers have failed.
Anderson took what could be an important step toward shoring up support among Republican activits Aug. 14 with the naming of Mary Crisp, former GOP vice-chairman, to head up his national campaign orgazation.
Major challenges confronting the Anderdson campaign over the next few weeks include:
* Bringing significant numbers of Republicans and Democrats disenchanted with their own parties' presidential nominees into his camp.
* Raising substantial private funds to fuel a high-visibility, momentum-gathering pitch for voter support.
* Making clear his strong position on various issues, such as taxation, government spending, defense, the environment, foreign policy, and human rights -- and how they differ from those of both the Democratic and GOP nominees.
* Winning his suit to force the Federal Elections Commission to provide at least some matching funds for the Anderson campaign.
* Selecting a running-mate whose candidacy would add broad-based appeal to the ticket.
* Getting on the ballot in all 50 states.
Considerable progress has been made in the latter effort over the past few months, both in court rooms and in collecting needed voter signatures on nomination papers.
Federal courts in Kentucky, Maine, Maryland, New Mexico, and Ohio have overturned state laws under which the filing deadline had passed prior to Anderson's April 13 launching of his candidacy as an independent.
Nomination papers have been submitted in 35 states and the District of Columbia, and Anderson has been certified for a place on the ballot in at least 13.
Nomination papers are being circulated in the remaining 15 states and, campaign leaders are increasingly confident that the coming deadlines will be met with ease.
The latest victory, scored Aug. 12 in Pennsylvania, produced nearly 2 1/2 times the needed 48,134 voter signatures.
Anderson campaign activitists, are optimistic now that a substantial number of supporters of Sen Edward Kennedy will bolt their party and work for the congressman from Illinois.
They are elated over the announcement of support by Washington attorney Joseph Rauh, a former head of the Americans for Democratic Action, and indications from former Wisconsin governor Patrick J. Lucey that he too may get on the Anderson bandwagon.
"We've have had quite an influx of people who were backers of Senator Kennedy come in and volunteer to help us," reports John Ames, a Republican formerly in the Massachusetts House of Representatives and now a leader in the Bay State effort for Anderson. He notes that a portion of the time his candidate will be in Massachusetts on the four-day New England swing is set aside for people who might wish to offer their help to the campaign.