Nicola Zingaretti (right) is pictured with Italian deputy PM, Matteo Salvini | Filippo Monteforte/AFP via Getty Images Italian center left wants to build bridges with Macron New leader Nicola Zingaretti unveils Democratic Party’s EU election manifesto.

ROME — The new leader of Italy's center-left Democratic Party (PD) pledged on Tuesday to build bridges with other pro-EU forces in the next European Parliament, including French President Emmanuel Macron's La République en Marche.

Nicola Zingaretti, who took the reins of the PD last month, said the party would not form a group with En Marche, which has been trying to tempt parties out of the Parliament's traditional blocs. But, in a sign of the PD's willingness to work with Macron, an En Marche official, Caterina Avanza, is on its candidate list for next month's European Parliament election.

Zingaretti was speaking at the launch of his party's European election manifesto, which calls for common unemployment benefits and a minimum 18-percent company tax across the bloc, including for internet giants. The PD also wants to see qualified majority voting introduced at EU level for tax matters — an idea fiercely opposed by some governments.

Zingaretti said he had been in talks with Macron's party but the PD would remain in the main center-left bloc in the Parliament, the Socialists & Democrats. Yet he also said that pro-EU forces should cooperate closely to thwart nationalists and Euroskeptics, who are expected to make gains in the election.

"We will surely be part of the S&D but we are open to alliances with other pro-EU families ... We want to be a positive example," he said, adding: "The priority is for the pro-EU camp to unite against nationalist populists."

He said the decision to include Avanza on the PD's slate is part of a broader move. "We opened up our list of candidates to En Marche as well as left-wing and Catholic representatives," he said.

Zingaretti, who is also governor of the Lazio region, declined to set a public target for the PD in the election. POLITICO's latest projection shows the party on track to come third in Italy and win 21 percent of the vote — a big drop from the last European election, in which the PD scored almost 41 percent under then-Prime Minister Matteo Renzi. However, the party's projected result would be an improvement on its general election score last year of just 17 percent.

The PD leader also used the manifesto launch to attack Italy's government of nationalists and populists.

"Italy risks international isolation because the current populist government lacks any vision whatsoever and it wants to destroy the EU rather than change it," he said. "But I don't think they will win the election."

In order to limit the nationalists' surge, Zingaretti said, "Europe must change: Jobs, development and growth must be put back at the heart of it."

He complained specifically about lower tax rates in countries in Central and Eastern Europe, which have prompted businesses to relocate operations and jobs from Italy.

"We can no longer consider this acceptable and if we need to rediscuss the treaties that require unanimity, so be it," Zingaretti said.