Once again, European politicians are heading for Brussels for a make-or-break decision about Greece. After weeks of uncertainty, all the signs are that the much-debated €130bn (£110bn) bailout fund will be signed off by eurozone finance ministers today. It is difficult to overstate the importance that they do so.

Indeed, the stakes could hardly be higher. Greece must pay back €14.5bn next month. Without the €130bn loan, it cannot do so, raising the spectre of disorderly default and a forced withdrawal from the single currency. Such an outcome would be catastrophic: not only for Greece, but for the eurozone, the EU and the entire global economy.

Given the complexity of the euro's problems, it would be unrealistic to expect progress to be smooth. But with the Greek economy in its fifth consecutive year of recession, the latest bailout has proved trickier than ever. And the brinkmanship displayed by Europe's leaders over the last week has only made matters worse.

In fairness, it was Greece that caused the initial delays, as politicians struggled to agree an extra €325bn worth of savings and protesters rioted in the streets of Athens. But then it was European finance ministers' turn to vacillate, postponing last week's meeting to agree the deal pending further pledges that the cuts would continue regardless of the outcome of Greece's general election in April.

It is not that concerns are unjustified. The sums of money involved are truly vast; Athens' capacity to fulfil its side of the bargain is, at best, unproven; and the looming election only adds to the uncertainty. Without cast-iron assurances that Greece will change its ways, German taxpayers – who will shoulder much of the burden – understandably suspect they may be throwing good money after bad.

Even so, the back-and-forth of the last week has looked less like reasonable caution and more like a supercharged game of "who blinks first" designed to force ever harsher measures on to an already-reeling Greece. It is a tactic as dangerous as it is irresponsible.

The primary mechanism for upping the pressure on Athens has been talk of allowing a default. Until recently, Greece leaving the euro was unthinkable in eurozone policymaking circles. Now whispered discussions of a Greece-free future are gaining traction, backed by claims that the newly expanded rescue fund is big enough to contain the fallout that would result.

Not only does such talk downplay the incalculable risks of Greek default. It is also in danger of becoming a self-fulfilling prophecy, not least by adding to the mistrust increasingly souring relations on both sides. Anti-German feeling is alarmingly on the rise in Greece, while Germans lose patience in return. All is not yet lost. Thus far, for all the riots, the majority of Greeks still want to remain in the single currency. And the German Chancellor has just about kept German taxpayers on side. But time is running out.

Greece's future in the euro cannot rest on austerity alone. Neither can the Greek people wait for structural reforms to bear fruit. Eurozone leaders must spell out concrete stimulus measures for Greece, in return for austerity. And Angela Merkel must do more to explain to German voters how much more it will cost if Greece defaults. She must also make the case for the unpalatable corollaries of closer fiscal union, including expanding role for the European Central Bank and, ultimately, creating a transfer union. Most of all, however, the eurozone needs a clear statement of solidarity. The most damaging aspect of the last week's dithering is the sense that Europe is still undecided about how far it will go to rescue Greece. With so much at stake, this is no time for games.