With Germany, 's economic powerhouse, refusing to unleash fiscal stimulus and other governments taking time to reform their economies, responsibility is falling on the to bolster growth and fend off deflation.
It is arguably becoming more urgent. Euro zone inflation slowed to 0.3 percent last month, far below the target of just under 2 percent and in what the ECB sees as a "danger zone".
Growth, meanwhile, has stalled, with some of the euro zone in recession and the bloc as a whole just above water.
Printing money to buy bonds - known as quantitative easing, or QE - would in theory boost both inflation and add to growth.
Reflecting this, ECB President opened the door in a Nov. 21 speech to stronger stimulus. His deputy, Vitor Constancio, went a step further last week, saying the bank would be better able to gauge in the first quarter whether to buy sovereign bonds.
"Now, it's too soon to make that assessment but indeed in early 2015 we have to look and assess if the (existing) programs are having the effect that we are expecting," Constancio told in a television interview.
That has many looking to the ECB's March 5 meeting for a QE launch. The two before then - in December and January - are seen as too soon; afterwards some believe it may be too late.
The bank has already begun buying covered bonds and bundled loans known as asset-backed securities (ABS) to try to stimulate those markets and generate new funding options for smaller firms, as well as to also increase the size of its balance sheet, or the amount of money being pushed in to the economy.
But these measures may fall short of the bank's goal of expanding its balance sheet back to levels seen in early 2012 - around a trillion euros higher than today. Inside the ECB, the balance sheet size is key to determining whether to launch QE.
Draghi's words and updated forecasts from ECB staff will be closely scrutinized when the bank holds its December policy meeting on Thursday, but this week is too early for the ECB to decide on QE.