Gorbachev Stuns Ally on Economy : Soviet Union: He rejects Prime Minister Ryzhkov’s moderate plan, favoring a quicker move to a free market.

President Mikhail S. Gorbachev went before Parliament today and rejected the moderate economic plan his prime minister had just presented to the body, instead endorsing a more radical blueprint for a 500-day switch-over to a market economy.

The stunning statement reflected dwindling confidence in Prime Minister Nikolai I. Ryzhkov and put Gorbachev closer to the position of radical reformers such as Boris N. Yeltsin.

Yeltsin, the Russian republic president, asked the republic’s Parliament last week to approve a radical reform plan drafted by Stanislav Shatalin, a Gorbachev aide.

Shatalin’s plan would transfer enormous authority from Parliament to the legislatures of the republics, which would then have the power to scrap centralized economic planning, introduce market mechanisms and legalize private property.

Gorbachev rejected Ryzhkov’s plan but said elements of it would be combined with Shatalin’s plan. He said the Shatalin program appeals more to him because it integrates “the ideas of constituent republics.”

“If there is a real plan to stabilize finances, money circulation, the ruble and the market, then we should adopt the Shatalin idea,” Gorbachev said. “We should try and work out a single document, and we are nearing it.”

He has avoided explicitly expressing a lack of confidence in Ryzhkov, a close ally, but his statements sparked new speculation that Ryzhkov would step down soon.

Gorbachev said he would present a plan on Wednesday that would be very close to the more radical plan proposed earlier by Yeltsin. A commission with members appointed by the two men has been trying to draft a common document for several weeks.

Ryzhkov’s speech drew fire from lawmakers in the national legislature, and Gorbachev responded with a warning against “shaking up all the political institutions in the country,” the Tass news agency reported.

“This is unacceptable. In this case, we shall bury everything we have achieved over these five years,” said Gorbachev, who became general secretary of the Soviet Communist Party in 1985.

No prime minister in 73 years of Soviet history has been forced to resign because Parliament refused to endorse his program.