MILAN — Italy's president said Friday he will take a few days to consider how to break the country's political logjam after another round of talks failed to establish which political force could best lead a coalition government.

President Sergio Mattarella told reporters in Rome after the second round of political talks that he had advised all of Italy's political blocs "of the necessity for our country to have a fully functional government." He cited the "urgency" created by the escalating trade war between the United States and China, the prospect of U.S. airstrikes against Syria as well as a European Council meeting in June.

"I will evaluate how to get out of the impasse," Mattarella said.

Italy could be tapped for a support role in any U.S. airstrikes, including use of air space, as it has with past military actions in the Mediterranean. After their meetings Thursday with Mattarella, the leaders of the two populist parties that are dominating the talks both emphasized Italy's role in NATO to assure allies.

Luigi Di Maio, the leader of the populist 5-Star Movement, called for an investigation into the chemical weapons attacks in Syria, and said he would seek a solution through diplomacy.

The head of the center-right bloc, Matteo Salvini, who has strong Russian ties and has expressed doubts that the Syrian government was behind the chemical weapon attack, expressed "loyalty" to NATO while adding he was "strongly against any unilateral action" in Syria.

Former Premier Silvio Berlusconi once again solidified his role as a major stumbling block to the creation of a government alliance between the 5-Star Movement and the center-right bloc led by Salvini, to which Berlusconi belongs.

Di Maio of the 5-Star Movement again made clear he will not enter into any government that includes Berlusconi, while Berlusconi rejects the 5-Star Movement as undemocratic.

That has led to an impasse that has shifted little since Italy's inconclusive March 4 national vote. The 5-Star Movement won as the largest party with 32 percent support in the vote, but the center-right bloc led by the far-right League and including Berlusconi's Forza Italia party and the extremist Brothers of Italy won 37 percent support.

In a show of unity, the leaders of the three parties in the center-right bloc met with Mattarella on Thursday.

But cracks showed as the 81-year-old Berlusconi pantomimed as Salvini read political priorities from a statement, clearly not pleased to be on the sidelines. Then, after ushering Salvini and the Brothers of Italy chief away, Berlusconi grabbed the microphone and made another swipe at the 5-Star Movement just moments after Salvini had made an opening to them.

"Do your job well," Berlusconi told journalists. "Know how to distinguish who is a democrat and who doesn't know the ABC's of democracy. "

Di Maio said Berlusconi's "bad joke" at their expense "demonstrated that the center-right still hopes" to form a government with the center-left Democratic Party — something that Salvini has expressly ruled out.

With no majority shaping up, Mattarella is unlikely to call another round of talks "absent positive developments," said Wolfango Piccoli of the Teneo Intel consultancy.

If he can't find a party leader who can muster enough support to form a new government, Mattarella could tap someone like the president of the Senate to explore possible government coalitions.

He could also pick a political figure — most likely someone from the center-right — and give them the chance to formalize a majority in parliament.