ATHENS—Greece’s international creditors are poised to present the country with the outlines of a bailout deal that amounts to a take-it-or-leave-it offer, a move aimed at breaking a monthslong stalemate but which risks a political backlash and even a government collapse in Athens.

The plan marks a sharp shift in tactics by Germany, the IMF and other Greek creditors, who have lost patience with what they see as months of fruitless dialogue with the Athens government. Lenders drafted the proposed deal after key leaders, including German Chancellor Angela Merkel, met in Berlin late Monday to overcome their own divisions on how to keep Greece from bankruptcy and an exit from the euro.

European officials say Greek officials, which are expected to be shown the creditors’ proposal Wednesday, will now be asked to accept the terms with, at most, minor changes. Greek Premier Alexis Tsipras is slated to visit European Commission head Jean-Claude Juncker the same day in Brussels, where the lenders’ demands as well as Greece’s conflicting ideas are likely to be discussed.

Greece, fast running out of cash, likely needs some sort of help by mid-June to repay a series of IMF loans falling due. The country is believed to have enough cash to repay a €300 million ($327 million) payment due to the IMF on Friday. But European officials say Athens probably can’t meet further IMF repayments in June totaling about €1.25 billion unless it gets fresh financing in some form. Without a large subsequent cash injection from lenders, Greece faces a debt default in late July that could ultimately push the country out of the euro.

But the policy conditions in the creditors’ proposal—whose details remained under wraps but include fiscal austerity, privatizations, and overhauls of pensions and labor law—could prove extremely challenging for Mr. Tsipras to accept without sparking a rebellion within his ruling coalition.