Tsipras's conservative rival, New Democracy leader Bangelis Meimarakis, remained within spitting distance before Sunday's ballot, however, after a three-week run-in which the two men's ratings have rarely been more than a half a point apart.
None of the surveys released on Friday suggested either Tsipras or Meimarakis would win an outright majority, setting the scene for coalition talks once the result becomes clear early on Monday.
The result is seen as crucial beyond Greece, which found itself almost ejected from the euro zone earlier this year.
The winner of the vote will need to oversee deep economic reforms required for an 86 billion euro ($98 billion) bailout brokered in August, a recapitalization of the country's banks, and the unwinding of capital controls imposed this year to prevent an implosion of the financial system.
Tsipras led in six polls released on Friday evening -- the last day in which polling and campaign are allowed -- trending further ahead of conservatives and with one giving him a 2.5 point lead.
Meimarakis won a single poll on Friday, the first of the day.
"Not one vote should be lost, we should not be beaten by abstention," Tsipras said at a rally in Athens' central Syntagma Square. "An abstention is a victory for New Democracy."
Tsipras was boosted on the podium by some leading lights from the European left, including Pablo Iglesias, head of Spain's Podemos party.
At his final rally on Thursday, Meimarakis focused on what he called Syriza's "false promises" to Greeks about ending the austerity tied to the country's international bailout, and its eventual acceptance on what some see as worse terms.
"It's high time we did away with incompetence. The Syriza experiment ends on Sunday," he said.
Coalition likely
Neither party is expected to secure the roughly 38 percent share of the vote needed for a majority in the 300-seat parliament, meaning a coalition is a near certainty.
Friday's polls broadly showed that, with the bonus of 50 seats given to the party with the most votes, Syriza could easily forge a coalition with the centrist To Potami party and the socialist PASOK.
Most parties in the election -- including Syriza and New Democracy -- are committed to the bailout, albeit with different emphases on such things as labor reform. Polls give all the relatively pro-bailout parties combined support of around 65 to 70 percent of the vote.
But there may be some concerns if Greece cannot form a stable government quickly.
Given that Greece's compliance with the bailout program is at issue, many at European Union headquarters in Brussels and in other European capitals would like to see a broad coalition emerge from the election.
But Syriza, forced to concede the bailout in August with the threat of a disorderly exit from the euro zone looming, has ruled out any pact with New Democracy, which it regards as part of an old guard partly responsible for Greece's economic woes.
The two parties also disagree on pivotal matters such as freeing up the labor market, collective bargaining and immigration.
New Democracy is willing to join a grand coalition if it wins the most vote. He has accused Tsipras of not wanting to cooperate because he does not really want to comply with the bailout reforms.
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