Sen. Christopher J. Dodd (D-CT) yesterday described as "glaring" the failure of the Bush administration to sign a 1989 United Nations treaty on the rights of children, as three senior Republican senators were circulating a letter urging President Bush to join the 135 heads of state who have done so.

"The world looks to us to take a leadership role on issues like this," Dodd said at a news conference. "For us to be a non-player is intolerable."

The letter to Bush from Sens. Robert J. Dole (Kan.), Richard G. Lugar (Ind.) and Mark O. Hatfield (Ore.) expresses "concern" that the United States is among a small group of non-signers that includes Iran, Iraq, Libya, Ethiopia and South Africa.

The Convention on the Rights of the Child, adopted by the United Nations in 1989 after a decade-long drafting process in which the United States played a central role, asserts the rights of children under 18 to develope their full potential, free from hunger, want, neglect, exploitation and other abuses.

It won the speediest approval of any international human rights treaty, ratified by the necessary 20 countries within nine months. To date, 77 nations have ratified it and another 58 have indicated their intention to do so, including all major Western democracies except the United States. Last fall, the Senate approved a non-binding resolution urging the administration to sign the treaty.

A legal adviser in the State Department, where the treaty is under review, said the administration's main reservations center on states' rights issues and a constitutional question of whether basic human rights in this country can be guaranteed by an international treaty.

"In our constitutional form of government, we view basic rights as limitations on the power of government to do things to the individual, rather than requirements that the government do things for people," said the official, who asked not to be identified.

He also noted the convention contained a number of specific provisions that conflict with state laws - most notably, a prohibition against capital punishment for minors.

Supporters of the treaty - including more than 150 human rights, religious, legal, labor, health and social welfare organizations in this country - argue that the administration should sign it and send it to the Senate for ratification with reservations, as it often does with international conventions.

"Some of the concerns may be valid, but the issue will never be joined until they send it to the Senate," said Craig H. Baab, a government relations official with the American Bar Association, which supports ratification of the treaty.

Dodd said yesterday he believed one reason the administration has taken a go-slow approach is that Sen. Jesse Helms (R-N.C.), the ranking minority member of the Senate Foreign Relations Committe, voiced concern about the absence of any language on abortion.

Conservative groups also have said they fear the treaty, in asserting that children have state- guaranteed rights, would weaken the role of parents. "Will the U.N. decide it is `neglect' not to establish government day-care centers?" Phyllis Schlafly, head of the Eagle Forum, asked in an article opposing the treaty.

Legal experts said the treaty would not have the force of law in this country but would be a standard by which the world community can gauge human rights.