Four avant-garde theater performers are suing the National Endowment for the Arts, contending they were denied funds for political reasons. Karen Finley and Holly Hughes of New York, John Fleck of Los Angeles and Tim Miller of Santa Monica filed a lawsuit in federal court Thursday asking for the $23,000 grants for which they applied - or at least review of their applications. The suit, filed on the artists' behalf by the American Civil Liberties Union, claims the NEA ``violated their First Amendment rights by denying their applications for impermissible political reasons.'' Josh Dare, a spokesman for the NEA, said today that the agency had no immediate comment on the suit. Grants for the performance artists, known as the ``NEA Four'' in arts circles, received unanimous approval in February from a peer review board. But NEA chairman John E. Frohnmayer vetoed the grants on June 29, and last month rejected appeals of his decision by the artists. He was named as a defendant. When Frohnmayer vetoed the four grants, he refused to give any reasons, citing a longstanding policy against discussing grant rejections. In an unusual departure from that policy late in August, the NEA issued a statement saying that Frohnmayer decided against giving the four grants because the artists' work would not ``enhance public understanding and appreciation of the arts.'' Congress, at the urging of Sen. Jesse Helms, R-N.C., last year amended the NEA appropriations bill for the current fiscal year to prohibit federal support for works that ``may be deemed obscene.'' The action came after controversy arose over exhibits by artists such as the late photographer Robert Mapplethorpe, whose work included sexual themes. The four who sued Thursday, each of whom had received NEA grants in the past, do monologues and other stage routines that generally deal with politics, racism and sexual oppression and frequently include strong sexual content. The performers had been singled out by conservative members of Congress as examples of the NEA's willingness to subsidize works that might be offensive.