Moments of high drama have become routine for Yeltsin. Last week, looking and sounding sharper than he has since the summer campaign, Yeltsin dismissed nearly his entire cabinet. Surviving: Prime Minister Viktor Chernomyrdin and Anatoly Chubais, his former chief of staff, who will now be first deputy prime minister and effective economic czar. By the end of the week, Chernomyrdin and other officials were dropping hints that the new cabinet–which will be named just before Yeltsin leaves for a scheduled summit in Helsinki this week with President Bill Clinton–will mark the return of reform-minded liberals: ““people who have new, fresh ideas,’’ as Yeltsin put it. The question now is, how many of his market-oriented disciples will Chubais be able to install? And, more important, will a notoriously fickle president stick by them when their policies prove controversial?

The first hint that Yeltsin was planning a shake-up came in his March 6 state-of-the-nation speech: ““I am not pleased with the government. The executive branch has proved incapable of working without the president’s using his whip.’’ It was audacious–an indictment of his own regime. The president plainly wants a clean break with the past two years of drift and decline. He may have appointed the people who run a government that has been unable to meet its basic obligations–like paying pensioners and soldiers–but the problem was, Yeltsin said, that he hadn’t been around to ““yell at them’’ because of his health.

Yeltsin clearly intends to regain control of his own government–with important help from Chubais, who guided Yeltsin’s winning campaign last summer and singlehandedly ran the Kremlin as chief of staff while Yeltsin was sick. The young economist is at once the president’s right arm and the most loathed political figure in the country. Some 90 percent of Russians view Chubais negatively, because he has presided over the massive privatization program that enriched only well-connected businessmen.

In Helsinki this week Yeltsin is likely to offer Russia’s grudging acceptance of the North Atlantic Treaty Organization’s eastward expansion in return for more economic aid from the West, as well as concessions on troop deployments in the new NATO countries and further, sharp cuts in nuclear arsenals. But the legacy of Boris Yeltsin’s second term will be written at home, starting immediately. Chubais’s new economic team must arrest what has turned into a gradual descent toward Third World-style poverty. He has to make sure that wealth begins to trickle down. Tax reform is critical to resolving the budget disaster, but it must be passed by a hostile Parliament. Crafting a new safety net, so that companies can restructure without fear of social chaos, is equally urgent.

Boris Yeltsin showed again last week that he loves the grand gesture. But his history has been to make them and then disappear. To repeat that pattern now risks disaster.