Hoffa Challenged

WASHINGTON, Sept, 24--Senate investigators today challenged the credentials of James R. Hoffa and 89 other delegates to a Teamsters Union convention at which Hoffa hopes to win the post of president.

The challenge came from Robert F. Kennedy, chief counsel of the Senate Rackets Committee, and Sen. Mundt (R-S.D.), a member of the inquiry group.

They contended the election of Hoffa, Midwest boss of the teamsters, and other delegates from Locals 299 and 357 in Detroit was not conducted in accordance with the union's constitution.