NEWS ANALYSIS : Once More, Yeltsin Puts Himself in Line of Fire : Russia: His strategy is treacherously double-edged: If his reforms fail, so do his political fortunes.

Once again, Boris N. Yeltsin, the bearlike Russian Federation president who courageously faced down the Soviet army’s tanks, has put himself right in the line of fire.

And this time may be even more dangerous.

In a make-or-break speech on economic reforms to the Russian Federation Congress of People’s Deputies, Yeltsin on Monday proposed a host of painful steps, including the freeing of all prices from government controls. He then offered to take direct responsibility for the plan’s success by combining the job of Russia’s prime minister with his presidential duties.

The idea was pure Yeltsin, the same manifestation of take-charge leadership that led him to clamber atop a Soviet armored vehicle in the early, uncertain hours of the August putsch and throatily denounce the whole venture as illegal.

“I am addressing you, determined to embark on the path of profound reform, and I ask for support from all segments of the population,” Yeltsin told all of Russia in a live television broadcast. “The time has come to take key decisions, and act at last.”

By choosing not to name a new prime minister--a step that had been widely expected since the departure of Ivan S. Silayev--and taking the job himself, Yeltsin will infuse the bruising reform agenda he wants with his immense prestige and popularity. But his choice of strategies is treacherously double-edged.

For if the reforms fail, so do Yeltsin’s political fortunes.

“This is a step of the utmost responsibility, but I greatly fear that the president in this way is depriving himself of a way out. And along with him, the democratic forces are cut off as well,” said Sergei N. Yushenkov, a leader of Russia’s Radical Democrats.

Vladimir N. Lysenko, the head of Russia’s Republican Party, observed: “Boris Yeltsin is the only man capable of convincing the people, because of his extremely high prestige. To head the government during this period would be suicidal for anyone else, since the people’s reply to the reforms is bound to be vigorous. There will be rallies and strikes.”

Yeltsin himself surely recognizes the immense risks involved but told the congress that the dire straits that Russia now finds itself in leave him no choice. “May this not seem an exaggeration, but we, in fact, are entering a historical period similar in its degree of responsibility and tension of forces (as the putsch),” he said. “Now, we must all work as we worked during those August days.”

Yeltsin, a political fixture in Moscow since 1985, has seen firsthand what the cost of unpopular economic policies can be. His former Politburo colleague, Nikolai I. Ryzhkov, saw his standing as Soviet prime minister plummet after plans were unveiled in the summer of 1990 to double the price of food. He left office virtually in disgrace.

Widespread dislike and hatred of Ryzhkov’s successor, Valentin S. Pavlov, began not with his participation in the abortive August putsch but with a decision months earlier to suddenly withdraw 50- and 100-ruble bills from circulation, a stroke of the prime ministerial pen that wiped out many people’s life savings.

Now, if Russian lawmakers agree, it will be Yeltsin’s turn.

Already, in fact, there are vague stirrings against the hero of August. The acclaimed populist critic of yesteryear is also the No. 1 bureaucrat in Russia and thus fully accountable in the public mind for its crushing list of woes.

The “White House,” Russia’s government headquarters that was the scene of the most dramatic moments of the short-lived coup, is now being picketed by workers worried by looming price rises.

Trade unions, many of which were once Yeltsin’s allies, also seem to be increasingly dubious or hostile, although to some degree their leaders are hunting for grass-roots, bread-and-butter issues to build up the credibility of the unions and themselves.

Igor Klochkov, chairman of the Federation of Russian Independent Trade Unions, has announced that Russian workers will stage a warning strike Nov. 13 unless a long list of demands, mostly economic in nature, are met by the leadership.

Although Yeltsin’s credit may still be strong among most of the population, he does not have much time to make the reforms work. By his own account, more than half the families of Russia today live below the wretchedly low poverty line, and life is getting tougher for most as winter arrives.

Yeltsin asked Russians to be patient, telling them there is no reason for panic and that he is convinced Russia can ride out the winter months. But he cautioned people that a real upswing in their lives cannot be expected for at least a year.

“All of us will suffer the pain for about six months, but then prices will start getting lower and consumer goods will appear on the counters, and by the fall of 1992, stabilization of the economy will set in, bringing gradual improvements in people’s lives,” he said.

To minimize the reforms’ impact, and also shore up his political flanks with the classes that have been among his most die-hard supporters, Yeltsin said there must be extraordinary measures of assistance to the poor and disadvantaged, from soup kitchens to boarding houses for the homeless.

Time and again, Yeltsin returned to the putsch and the resolve shown by pro-democracy forces as a metaphor for how Russia must face the trials that surely lie ahead.

“We have defended our political freedom,” he told the assembly. “Now we need to provide economic freedom as well.”