Leader Alexis Tsipras says his government and the country face “hard work and struggle”.

Greek voters have returned Alexis Tsipras, the former prime minister and leader of the left-wing Syriza party, to power with a strong election victory.

With 51 percent of Sunday’s vote counted, Syriza had 35.5 percent of the votes, with the conservative New Democracy (NDP) coming in second with 28.1 percent.

The right-wing Independent Greeks party were in seventh place with 3.7 percent, just above the three percent threshold needed to enter parliament.

After the initial results were announced, Alexis Tsipras tweeted: “In front of us lies the long road of struggle and hard work.”

OPINION: The unbearable lightness of Greek democracy

The head of Independent Greeks, Panos Kammenos, said that his party would join Syriza in forming a coalition government.

“From tomorrow morning, with Alexis Tspiras as prime minister we will form a government,” he said.

The results give Syriza 145 seats in the 300-member parliament, and 10 for the Independent Greeks, meaning the two parties can form a government with a slim majority of five seats.

Kammenos’ party was Syriza’s junior coalition partner in the short-lived seven-month government that was elected last January on an anti-bailout platform, but with a much larger parliamentary majority.

Al Jazeera’s Simon Marks, reporting from Thessaloniki, said Syriza’s victory will come as a relief to the institutions in Brussels “as the newly elected parliament has been provided with the mandate it needed to move ahead with implementing the country’s recently agreed bailout package”.

Tsipras resigned last month, triggering elections after facing a rebellion within Syriza over his policy U-turn in accepting a painful third bailout.

The head of main opposition NDP conceded the elections, congratulating Tsipras, calling for a government to be quickly formed.

“The election result appears to be forming comprehensively with Syriza and Mr Tsipras coming first,” NDP’s Meimarakis said.

“I congratulate him and call on him to form the government that is necessary, and bring the [proposal] to parliament.”

Nine parties hoped to enter parliament [Reuters]

Early results and exit poll projections showed Syriza was falling short of an outright majority, meaning it will need coalition partners to form a government. During the campaign, Meimarakis had said his party would join Syriza in a national unity government – something Tsipras has repeatedly ruled out.

Tsipras recently had to accept economic reforms in exchange for a $96bn bailout package from Greece’s international creditors.

He had to agree to the eurozone bailout despite the fact that 61 percent of Greek voters in a July referendum overwhelmingly voted against an earlier offer that insisted on austerity measures.

The bailout Tsipras agreed to, which kept Greece in the eurozone, was widely seen as more severe than the original offer and included new taxes and spending cuts.

READ MORE: An election without aspirations in Greece

While Tsipras’ supporters say he went down fighting, Meimarakis has described his seven months in government as “an experiment that cost the country dearly”.

In January, Syriza won the general election with 36.34 percent of the vote, followed by the New Democracy bloc at 27.81 percent. The left-wing party had formed a coalition with the Independent Greeks.

With reporting from Barnaby Phillips in Athens