New rules changing the way scarce organs are allocated for transplant will take effect by January under an agreement reached by the Clinton administration and members of Congress who originally hoped to delay the changes.

The rules issued by the Department of Health and Human Services would force the United Network for Organ Sharing, which runs the transplant system, to send organs to the sickest patients first, no matter where they live.

The current system is based largely on geography and supported by many transplant centers whose lucrative programs depend on locally donated organs.

The network and its allies have strenuously fought the proposed changes. But now the network plans to go along with the new rules.

Without congressional action, the new rules would take effect next week. Under the agreement struck late Wednesday, they will take effect after 21 days of public comment and another 21 days for HHS to review those comments. The six-week clock will begin once the spending law is enacted, possibly as soon as next week.

The key, participants said, was Rep. John Edward Porter (R-Ill.), who chairs the Appropriations subcommittee that handles HHS. Porter now supports the HHS plan after vigorously opposing it. He changed his mind after Illinois got into a dispute with Wisconsin, Minnesota and the Dakotas: Wisconsin and its neighbors did not want to share their livers with Illinois, even for the most ill, as the network had ordered on its own.

The dispute prompted Illinois officials and transplant centers to change their position on the HHS rule. Porter followed suit.