Textron Inc., vice president Robert H. Charles, newly elected president of the National Alliance of Businessmen yesterday urged business leaders at local and regional levels to help generate new jobs for an American "underclass" of more than 7 million unemployed individuals.

"We must try harder . . . the unemployment problems of the underclass . . . require extraordinary effort," Charles told the NAB. The alliance is a government-mandated group originated by President Johnson in 1963 and given the challenge of finding jobs for disadvantaged adults. Vietnam veterans, needy youths and qualified former offenders.

While vowing to expand the NAB's national efforts to convince business about advantages of cooperating with the jobs program, Charles said a major emphasis in the coming year will be at the local level.

More business representation is needed on regional NAB advisory boards to mount effective job-pledging operations, the former assistant Secretary of the Air Force added.

Charles was elected by the group's directors along with the NAB's new chairman, Textron chairman G. William Miller. The Textron officials succeed V. J. Skutt, chairman of the Mutual of Omaha Cos., and Mutual of Omaha vice president William G. Murphy in the NAB's top two posts.

Some 100,000 U.S. companies have taken part in NAB activities in 130 cities, with executives for local NAB offices "on loan" to the job group and paid by their firms. More than 5 million jobs have been identified by NAB since its inception.