Eleventh-hour talks to avoid Greece defaulting on its debt and plunging the eurozone into crisis intensified at the weekend with Greek officials flying to Brussels only days before a meeting of Europe’s finance ministers that many regard as a final deadline.

Almost five months after he assumed power, the Greek prime minister, Alexis Tsipras, has come to a fork in the road: either he accepts the painful terms of a cash-for-reform deal that ensures Greece’s place in the single currency or he decides to go it alone, faithful to the vision of his anti-austerity Syriza party. Either way, the endgame is upon him.

Thursday’s meeting of eurozone finance ministers is viewed as the last chance to clinch a deal before Athens’s already extended bailout accord expires on 30 June. “It is in his hands,” Rena Dourou, governor of the Attica district, told the Observer. “Tsipras, himself, is acutely aware of the historic weight his decision will carry.”

The drama of Greece’s battle to keep bankruptcy at bay has, with the ticking of the clock, become ever darker in tone. What started out as good-tempered brinkmanship has turned increasingly sour as negotiations to release desperately needed bailout funds have repeatedly hit a wall over Athens’s failure to produce persuasive reforms.

“It is as if they work in Excel and we work in Word,” said one insider. “There just seems to be no meeting of minds.”

Last week the mood became more febrile as it emerged that Eurocrats, for the first time, had debated the possibility of cash-starved Athens defaulting. The revelation came amid reports that Germany’s chancellor, Angela Merkel, was resigned to letting Greece go.

Berlin is by far the biggest contributor to the €240bn bailout propping up the near-bankrupt state. Last week, the EU council president, Donald Tusk, ratcheted up the pressure, warning: “There is no more time for gambling. The day is coming, I am afraid, that someone says the game is over.”

On Saturday Greek finance minister Yanis Varoufakis hit back, telling Radio 4 that he did not believe “any sensible European bureaucrat or politician” would seriously contemplate the country’s euro exit. “The reason why we are not signing up to what has been offered is because it is yet another version of the failed proposals of the past,” he said.

The persistent demand of foreign lenders for pension reform, given the scale of austerity already undertaken in a country that has seen its economy shrink by more than a quarter in the past five years, was not only silly but plainly a deal-breaker, he said. “It is just the kind of proposal that one puts forward if you don’t want an agreement,” insisted the academic-turned-politician.

With both sides seemingly determined to take negotiations to the brink, the nerve-racking game of poker was raised a notch yesterday as Tsipras’s closest aides resumed talks with technical teams in Brussels. The EU and IMF say the ball is now in Greece’s court. Following his rejection of their demands as “absurd” last week, the young premier is hoping the officials will be able to bridge outstanding differences on the basis of a new set of “counter proposals”.

Publicly, the government says it is closer than it has ever been to a deal, but in private EU sources say the Greek government’s proposed measures still run too close to the “red lines” that Tsipras has refused to cross in terms of pension cuts and labour deregulation.

In a statement released by his office , the leader was quoted as saying that, if a compromise agreement was viable, his government would support it, no matter what. “But if what Europe wants is division and continuation of subordination we will again … say the big no and we will give battle for the dignity of the people and our national sovereignty,” the statement quoted him as saying.

Tsipras’s robust defence of what Greek people believe are their rights has played well with a population both worn out and humiliated by crisis. Support for him has never been higher.

Neither, ironically, has support for Greece’s continued membership of the eurozone itself. “Even if we achieve very little, we will know that we have held our heads high,” said Vangelis Pavlatos, an actor, in what has become a common refrain. But the prolonged talks and the uncertainty they have engendered has also sounded the death knell for the real economy and a banking system that has been depleted by worried savers. Panic is on the rise; so, too, is the unmistakable sense that whichever way they go – and an extension of the current programme may well be the end result – pride will soon be replaced by hardship.

“Everyone knows that a new deal is going to mean more austerity,” said Takis Leonidopoulos, among the hundreds of accountants who took to the streets on Friday in protest over projected tax rises.

“But if there is no deal we will likely see capital controls, our bank savings will be up in the air, salaries could stop, it’ll be ordinary people who will pay the price. What we are looking at is misery either way,” he sighed. “The big question – and be sure to write this – is how are the Greeks going to react?”