Extremely heavy police protection will be in effect today for an expected bitter confrontation between Nazis and counterdemonstrators in the white, working-class Marquette Park neighborhood on Chicago's southwest side.

A rally by a few dozen self-styled storm troopers in brown shirts with swastika armbands is set for 1 p.m. (EST) as a federal court-approved alternative to a march originally planed two weeks ago in the heavily Jewish suburb of Sokie.

A coalition of 42 civil rights, religious and community groups that was formed in the face of the threatened Skokie demonstration is split on whether to counterdemonstrate today, but police are braced for a potentially violent clash.

Among coalition groups that plan to confront the Nazis are Operation PUSH, headed by the Rev. Jesse L. Jackson, and the NAACP. The militant Jewish Defense League, which is not part of the coalition, has treatened to stop the rally with violence.

All days off were canceled for police in the Chicago Lawn District, which includes Marquette Park. Between 400 and 500 uniformed officers, some on horseback, are expected, with another 150 in reserve at nearby Midway Airport.

A similar show of strength by police prevented violence when a few Nazis demonstrated June 24 in a federal building plaza downtown. That demonstration originally was planned as a warm-up for the Skokie march that was called off by Nazi leader Frank Collin after he won approval from U.S. District Court Judge George N. Leighton for the Marquette Park rally.

The Chicago Park District petitioned in vain for the U.S. Supreme Court to stay Leighton's ruling, which ordered the district to issue a rally permit without requiring an insurance bond. After Justice William Brennan denied the stay Friday, Park District attorney Richard Troy announced, "All legal appeals have been exhausted. We must now issue a permit. We certainly hope that Frank Collin, now that he's achieved his victory, will call it off like he did in Skokie." When Collin was informed of Troy's statement, he laughed and said he expects about 1,000 Nazi sympathizers at the rally.

Mayor Michael A. Bilandic issued a statement urging citizens to stay away from Marquette Park today as "a form of passive resistance" to the Nazis.

But Bill Watkin, a spokesman for some of the coalition groups supporting a counterdemonstration said, "Why is there a different agenda for Marquette Park than there was for Skokie? We are appealing to the leaders who stood so firm in Skokie to stand with us now."

A spokesman for the Southwest Parish and Neighborhood Federation, a coalition group that opposes any counterdemonstration said, "There is no more support for the Nazis in Marquette Park than there is in Skokie, but if the rally does have to take place we appeal to the good people of Marquette Park to leave it to the Nazis. We should not play into their hands and make this a battleground for crazies."