Until then, countries such as Spain and Italy had seen their borrowing costs - reflected in the interest rates on bonds they sell - rise to unmanageable levels. Investors were worried that the two countries could soon get to a point where they couldn't afford to handle their finances and be pushed into asking for a bailout.
That has already happened three times in the eurozone - with Greece, Ireland, and Portugal. The worry is that Spain and Italy are too big to bail out. If those countries fail to pay their debts on time, it could spark a financial crisis that could see the eurozone break up, spreading turmoil throughout the global economy.
Under Draghi's blueprint, the ECB would refrain from setting a public cap on government bond yields, according to the officials, who spoke on condition of anonymity. The plan will focus only on government bonds rather than a broader range of assets and will target bonds with maturities of up to about three years, they said.
The euro gained against the dollar Wednesday and European stocks advanced on the report. But an ECB spokesman referred to an Aug. 20 statement in which the Frankfurt-based central bank said it was misleading to report on decisions that haven't been taken yet.
Draghi told the European Parliament this week that the ECB needs to intervene in bond markets to wrest back control of interest rates in the fragmented euro-area economy and ensure the survival of the common currency.
Policy-makers were deliberating on the plan Wednesday, and Draghi was to announce Thursday whether it has been agreed to.
The officials said policy-makers are likely to adopt Draghi's proposal, with Germany's Bundesbank remaining the sole objector.
To "sterilize" the bond purchases, the ECB will remove from the system elsewhere the same amount of money it spends, ensuring that the program has a neutral impact on the money supply.
While the ECB doesn't expect to have to spend large sums of money on bonds, Draghi's plan calls for no limits to be set, two of the officials said.
Draghi will stress conditionality of the program, with the ECB likely to stop buying the bonds of any government that fails to meet the conditions it agrees to when it signs up for aid from Europe's rescue fund - a precondition for ECB action - two of the people said. Another proposal is for the ECB to sell the bonds it has bought if a country doesn't comply with the conditions, two of the officials said.
This article contains information from the Associated Press and Bloomberg News.