President Boris Yeltsin, ailing from heart disease and facing major surgery later this month, was urged today to transfer his authority temporarily to Prime Minister Viktor Chernomyrdin before the operation.

Doctors indicated they expect Yeltsin, 65, to have a coronary artery bypass, which involves using a healthy blood vessel to route blood around a partially blocked one. The operation restores an adequate supply of blood to the heart muscle. It is major surgery, requiring that a patient's breastbone be cut, the chest opened and the heart temporarily stopped. The surgery is planned for late September.

Yeltsin has not said whether he will invoke a clause in the 1993 Russian constitution to hand over power to Chernomyrdin, but the chorus of advice today urging him to do so underscored the sense of anxiety among political leaders that there could be a period of instability if Yeltsin remains incapacitated or absent but still in charge.