Greece's election campaign, the second in as many months, officially kicked off on Saturday as polls indicated that fears of expulsion from the eurozone have helped consolidate support for parties backing the tough terms under which Greece received a bailout to keep its debt-stricken economy afloat.

Signs of a nascent backlash against anti-bailout groups that took the country by storm in an inconclusive ballot two weeks ago have emerged with surveys showing that the conservative New Democracy party is beginning to rally voters on concerns that opposition to EU- and IMF-dictated austerity may lead Greece to the eurozone exit door.

Piling on the pressure, the visiting European parliament president, Martin Schulz, said that a €130bn rescue package reached with international creditors in March could not be renegotiated.

"Greece… shouldn't self-destruct," the German politician told the state-run TV channel NET. "Nor can we Europeans write Greece off. Greeks must believe in themselves." He implored the nation at the centre of Europe's escalating debt crisis to stay the course of tough austerity and structural reforms because that was the only assured way of boosting competitiveness.

Increasingly, the 17 June election is being portrayed as a referendum on the crisis-plagued country's desire to remain in the eurozone.

Schulz's appeal follows a series of similar exhortations by senior European officials who have insisted that repudiation of the tough terms that have allowed Athens to receive crucial injections of cash over the past two years would automatically pave the way to it leaving the 17-nation bloc.

Apocalyptic scenes have been invoked as policymakers have speculated over the chaos that would ensue if Greece, bereft of rescue funds, defaulted on its debt and reverted to its old currency, the drachma.

On Friday, the German chancellor, Angela Merkel, also weighed in, allegedly suggesting in a telephone conversation with the Greek president, Karolos Papoulias, that the nation hold a referendum on euro membership as part of the general election. The proposal was denied by her spokeswoman.

Antonis Samaras, whose New Democracy party emerged with the largest share of votes but fell far short of being able to form a government when Greeks went to the polls on 6 May, retaliated last week by reaching out to centrist forces that would fight against the vociferous anti-austerity bloc. He said his party would lead a pro-European "front of resistance against catastrophe".

The strategy appears to be paying off, with two polls showing the conservatives for the first time ahead of the radical left Syriza party. The leftwing alliance, a fierce opponent of the "inhumane" belt-tightening imposed in return for aid, had been the frontrunner since emerging as the surprise runner-up in this month's poll.

In an interview before a visit to Berlin for talks that will include discussions with representatives of the German government, Syriza's firebrand leader, Alexis Tsipras, reiterated his determination to "cancel" the loan accord, even going so far as to liken it to "assisted suicide".

But he also appeared to soften his stance, saying he hoped to initiate a "substantive dialogue" with Germany and France, which have bankrolled most of the €240bn in emergency aid earmarked for Greece.

"If you don't talk you can't find a solution and so far I believe there hasn't been any real discussion or political negotiation," he told the Observer. "The memorandum," he said, referring to the bailout conditions, "was a political decision that was taken without consulting the Greek people and it has proved catastrophic."

Tsipras's meteoric rise from marginal leftist to possible commander of the political scene has been backed by younger Greeks worst hit by the record levels of unemployment. The young politician has promised to reinstate jobs and pensions by nationalising banks, stopping the closure of state utilities and taxing the rich.

But among older Greeks, who still have vivid memories of military rule and the tumultuous politics of isolation, Syriza's anti-austerity platform has unleashed fears that, if he wins, the country will be playing with fire.

Although voters punished mainstream parties on 6 May for enforcing cuts that have seen wages drop by up to 40 % – and austerity rage has far from dissipated – it could just be that the fear factor is starting to take effect with a backlash that few would have imagined a week ago.