Two of New York's most powerful Roman Catholics - the mayor and the cardinal - are clashing over the rights of unmarried couples, both gay and heterosexual.

At Mass on Sunday, Cardinal John O'Connor spoke out against Mayor Rudolph Giuliani's proposal to grant domestic partners the same legal rights as married couples."An institution as fundamental as the family cannot be manipulated," O'Connor said in his homily at St. Patrick's Cathedral in Manhattan. "The institutional value of marriage must be upheld by the pub-lic authorities."

The cardinal, the spiritual leader for the nearly 2 million Catholics in the New York archdiocese, said that while the church will fight to protect human rights, it will do so only through actions "that do not abrogate the sanctity of marriage."

Giuliani countered that his position was "a healthy one."

"The cardinal has every right to preach and to argue for his moral point of view," Giuliani said. "But I think that my analysis of it is that this is a human rights issue."

Giuliani wants to ensure that unmarried and married couples are treated the same on everything from housing to parking permits to burial rights. A vote on his legislative proposal is expected in the City Council by late June.

Similar legislation is being considered in San Francisco and Seattle.