The Greek prime minister, Alexis Tsipras, is the first to say he relishes a fight. And, true to form, he upped the ante on Friday when he declared this weekend’s European parliament poll a vote of confidence in his government.

In comments that sent ripples through a political arena already at fever pitch, the leftist leader hinted that early elections could be in the offing if, as surveys suggest, his Syriza party is beaten at the ballot box.

“On Sunday, people may not be voting for a government, but they will be voting on the policies that will govern the country in the coming years,” he said, referring to tax cuts and pension benefits announced in the run-up to the contest. “If these measures are rejected, all prospects are open.”

The declaration was interpreted as a last-ditch bid to consolidate disaffected voters, who are also casting ballots in municipal and regional elections on the same day.

Ever the tactician, Tsipras has made a package of relief measures, to be enforced this year and next, the centrepiece of his quest to regain lost support as the nation gradually emerges from almost a decade of economic recession.

The leader, who turns 45 in July, first assumed office in January 2015.

With general elections due to be held by October, Sunday’s outcome is being viewed as a critical barometer of the mood at large.

No EU election has been quite like this. In the spirit of most Europeans, Greeks have invariably seen the race for seats in the 751-member European parliament as an opportunity to vent their spleen over unpopular government policies. But as the electorate heads to the polls for the first time in almost four years, the vote has assumed unprecedented significance.

Kyriakos Mitsotakis, the centre-right New Democracy leader, has cast the election as a referendum on his rival’s four-year term in office. All surveys have given the edge to the 51-year-old, who in an atmosphere of growing polarisation has appealed for consensus, pledging “to unite all Greeks and lead a great political change”.

Since assuming the party’s helm, the Harvard-trained reformist has sought to rebrand an old-school conservative party into a moderate force capable of attracting centrists.

Acutely aware of the battle that lies ahead, Tsipras has been criss-crossing Greece, firing up the crowds with turbo-charged rhetoric, berating the “old elite” that brought the debt-stricken country to the brink of financial collapse and promising to deliver better days.

Last week, as the campaign intensified, he hosted more than 50 school cleaners at the prime minister’s official residence, the Megaron Maximou, where he announced that they would receive a 10% pay rise and the same generous benefits as given to hazardous jobs.

“No other prime minister has ever invited us or spent any time listening to our demands,” Fani Tzouma, who attended the meeting as head of the Clean Gloves Association, told the Guardian. “We realise politics is at play, but he also accepted that ours is a difficult job, a dangerous job, and that it should be put on the list of hazardous professions.”

Addressing thousands in Crete ahead of a campaign finale in Athens on Friday night, Tsipras listed his government’s achievements despite the strictures of being in a bailout programme until last summer.

“Our opponents don’t understand the needs or desires of people. They don’t understand what €200 can mean to a pensioner, as that is the amount they leave in tips in fancy restaurants.”

Large sectors of Greek society were pauperised during the nation’s long-running struggle to keep bankruptcy at bay. Prolonged recession, underscored by the loss of 26% of GDP, followed the excoriating terms that Athens was obliged to meet in exchange for emergency bailout funds from the EU and IMF.

Tsipras’s once tiny party was catapulted into office on the back of fury over austerity, with Europe watching in horror as the politician vowed to tear up the bailout accords until he, too, buckled under the threat of the country being ejected from the eurozone.

With his own popularity dented, the politician has been at pains to reassert his leftist credentials, announcing the unexpectedly generous relief measures as a counterbalance to years of cuts, appealing to first-time voters and venturing where other politicians have feared to go.

In major cities, migrants and members of the Roma and LGBT communities have shown up in force at Syriza rallies.

Against the odds, Tsipras appears to have closed the gap, despite criticism from creditors who fear the relief measures could roll back years of fiscal progress, protests against his populist opportunism and charges of leading a gauche caviar lifestyle after local media published pictures of him lounging on a yacht.

A poll by Kapa Research on Thursday showed Syriza and its Progressive Alliance of centre-left parties had regained enough lost ground to trail New Democracy by 3.4 percentage points. With 11.1% of voters still undecided, Sunday’s poll showed all the signs of being a much closer race than expected.

Throughout his career, Tsipras has thrived on his ability to surprise, from giving in to creditors and changing course over bailout demands to negotiating a deal that saw North Macedonia adopt its new name earlier this year.

In a race where Europe has barely got a mention, one of his favourite mantras has been: “You don’t go into battle thinking you will lose.”