To jump-start growth and avoid deflation, many analysts say the most powerful policy arrow in Mr. Draghi’s quiver is to talk the euro sharply downward, which would bolster exports, increase the price of imports and ultimately, it is hoped, stimulate an increase in inflation.

“The euro is going to go down because it really needs to,” said Jens Nordvig, the global head of currency strategy at Nomura in New York. “The divergence between European and U.S. growth is very, very wide now.”