D.C. City Council Chairman Arrington L. Dixon started lobbying his colleagues yesterday to change a proposal that would legalize sexual intercourse between consenting children of similar ages.

The bill would allow sexual intercourse between children 12 years old and older, so long as one is not more than four years older than the other, and between children younger than 12 if one is not more than two years older than the other. It was approved unanimously by a council committee June 3 and is scheduled for a vote by the full council on Thursday.

Dixon said he would work with council member David A. Clarke (D-Ward 1), sponsor of the measure, to find a compromise age of consent lower than the existing 16, but more acceptable in Dixon's view to the general community than the proposed change.

Dixon has lately been able to put together compromises behind the scenes on several key issues, but it was unclear yesterday how the age-of-consent issue might be resolved. Supporters of the bill on the council's Judiciary Committee and in the community said they feared that the entire bill -- a sweeping revision of the city's sexual assault laws -- could be scuttled because of opposition to the section dealing with sexual relations between consenting children.

Under the current statute, any person having sex with a girl under 16 is subject to a jail term of up to life imprisonment. That section would apply even if the offending male was also under 16 -- for example, in the case of two 14-year-olds who have sex. So young people under 16 were violating criminal law whenever they had consentual sexual intercourse, although they have rarely been prosecuted.

Clarke said his bill is intended to take consentual teen-age sex out of the city's criminal code. Supporters said the change is justified since so many young people have sex before age 16 and since practically no teen-age youths are being prosecuted under the current law.

But opponents of changing the age of consent said that for the council to eliminate criminal penalties -- even if those penalties have rarely been enforced -- would have the effect of putting an official stamp of approval on sex between children. Sex between adults and children, and forced sex between children, would still be a crime.

"They [the bill's sponsors] are saying that since children are doing it anyway we might as well legalize it. That's what they said about gambling," said the Rev. John D. Bussey, a Baptist minister who last year led the unsuccessful fight to defeat the referendum that legalize a city-run lottery and daily numbers operation.

"I think it's insane," he said. "It's just plain insanity. These people [the council] have no sensitivity to right and wrong. There's no way these people on the City Council can be in their right minds."

However, a group of young people interviewed yesterday seemed generally receptive to the proposed change.

"We should be able to have experiences just like older ones [people]," said 11-year-old Darrell Duckett of Northwest Washington. "We shouldn't be able to do everything that they do, but we should be able to have sex."

Michael Smith, 15, said there should be no restrictions on kids having sex because "some kids may have the same feelings as adults, and so they may want to have sex."

Smith said the new law would not encourage teen-agers' sex and problems with teen-agers trying to deal with unwanted pregnancies. "Most friends I have who have had sex are careful nowadays. The girls use pills or other things and the guys use condoms. Last summer everyone was having babies. Not this summer, no more," he said.

The proposed legislation follows the pattern in about half of the 50 states, according to a report prepared by the American Bar Association. Some state legislatures are now scrapping the old carnal knowledge laws, written specifically to protect young girls, with reforms aimed at removing criminal penalties for sex between consenting teen-agers.

Supporters of that approach said that young people who have sex still could face civil suits, brought, for instance, by parents.

D.C. Corporation Counsel Judith W. Rogers said that her office has begun reviewing its files for the last three years to see how many young persons have been prosecuted under the current statutory rape law that prohibits sex with a girl unde 16 years old.

Rogers said that since 1979, only a dozen juveniles have been charged with sexual assault offenses. She said it was unclear whether any of them were cases of two young persons having consentual sex, with the girl being under 16 and the boy being charged with carnal knowledge.

Mayor Marion Barry said he would reserve comment on the issue until he has confered with Rogers. He promised to make a statement on Monday, before the bill is considered by the full council.

The entire sexual assault bill, recommended by the city's Law Revision Commission, scraps entirely or amends several laws that committee members considered outdated or antiquated, like the old statutes against seduction and prohibiting sodomy between consenting adults.

Under the proposed bill, there would be no criminal penalties for sexual activities between consenting adults, but a broader range of still penalties for a variety of forced sexual offenses not now specifically prohibited by law.For instance, the bill would impose penalties for sex, brought through force or coercion, with any person who is institutionalized or mentally incapable of resisting.