ROME - With markets tumbling around the globe, Italy's president promised emphatically Wednesday that Silvio Berlusconi will step down soon as premier and lavished honors on a leading economist, who instantly became Berlusconi's presumed successor.

Across the Ionian Sea, the debt crisis in Greece deepened with the breakdown of talks aimed at creating a power-sharing government to prevent the country from slipping into bankruptcy. The collapse came just minutes after the prime minister delivered a farewell speech to the nation.

The chaos reverberated around the world, and investors pulled money out of Europe. The Dow Jones industrial average plunged more than 3 percent, the euro slipped 2 percent against the dollar, and Italy's key borrowing rate spiked at a dizzying high of 7.4 percent.

Investors fear Italy might follow Portugal and Greece into begging for a bailout from its partners in the euro. But Italy's $2.6 trillion debt is far too great for Europe to cover.

On Tuesday, Berlusconi announced he would step down after Parliament passes a series of economic reforms to stave off financial ruin in Italy. But there was growing fear he doesn't have the will or the clout to push the measures through. And some worry the wily premier will try to stay in power.

On Wednesday, with the markets in turmoil, Italian President Giorgio Napolitano in effect put Berlusconi on notice that he and the world's markets are expecting Berlusconi to keep his word and leave soon.

Parliamentary whips feverishly worked out a timetable to ensure that the Italian Senate would give final approval Friday to the package of measures, aimed at stimulating growth and reining in debt, according to state TV. It said the lower house would do the same on Saturday, meaning Berlusconi could be out before the weekend is over.

Berlusconi's top political aide, Angelino Alfano, confirmed the scenario, saying on a TV talk show Wednesday night that Berlusconi would resign sometime between Saturday and Monday, as soon as the economic reform law is passed.

In a surprise move, Napolitano named Mario Monti, who runs the prestigious Bocconi University in Milan, as senator-for-life, an honor given to notable figures that bestows voting privileges in the upper house of Parliament.