A month after Draghi unveiled a bond-purchase program for struggling euro states that was hailed by many as a savior for the single currency bloc, investors are still waiting for Spainto bite the bullet and request a formal rescue.

Before it does, the ECB cannot act, and markets are likely to remain jittery. Spanish two-year note yields have climbed more than half a percentage point in the weeks since Draghi's plan was unveiled - a reminder that action not words are needed to resolve euro zone's three-year old crisis.

"Draghi will be careful, but he will put a little more pressure on Spain to ask for support, given that if that doesn't happen, market turmoil, market volatility could increase again," said Elwin de Groot of Rabobank.

Before the Italian ECB president's 1230 GMT news conference, the central bank announced that its governing council had decided to keep its main refinancing rate steady at 0.75 percent, a record low.

Analysts expect the bank to cut rates later this year, but only after the new bond program has started.