Italy’s president is today in talks as the country awaits news about whether an unknown law professor without any political experience will be approved as the next prime minister.

The country’s two populist parties – the anti-establishment Five Star Movement (M5S), and the anti-migrant League – announced a joint agreement naming Giuseppe Conte, 53, a lawyer and M5S member, as the next leader of the eurozone’s third largest economy, after Matteo Salvini of the League, and Luigi Di Maio, of the M5S, ruled themselves out.

Conte requires the approval of the country’s president, Sergio Mattarella, who met with Salvini and Di Maio on Monday evening and will hold further meetings on Tuesday.

The deal came after weeks of intense negotiations between Salvini and Di Maio, who are attempting to cobble together a government based on their shared views. The parties’ agenda calls for sweeping fiscal changes, a more confrontational stance against Brussels, and a tougher approach against migrants, including the creation of detention centres across the country.

“We obviously want a country that puts the interests of Italians first. We are ready to go, no one has anything to fear,” Salvini said following his meeting with Mattarella.

Late on Monday, Mattarella asked the two speakers of parliament – but not Conte – to meet him on Tuesday at the presidential palace to continue consultations.

After weeks of negotiation, when it seemed only an election over the summer might end the political impasse, the reality of the rocky road ahead and the elevation of a populist government to lead one of the EU’s largest countries seemed to hit home.

Fitch, the ratings agency, warned that the incoming populist government could pose a risk to Italy’s credit profile, and there was heavy trading in equity and bond markets amid questions about the groups’ Eurosceptic policies.

In Brussels, Conte’s nomination to be PM was met with puzzlement. “Nobody knows who he is and he is not even a high-profile academic,” said one EU official, noting that even Italians had been joking that the man who could be their next prime minister was less well-known than his namesake, the Chelsea FC manager Antonio Conte.

Lorenzo Codogno, a visiting fellow at the London School of Economics, said: “He will have no experience in government and he will be effectively catapulted into the job without having named the cabinet or decided the programme. I am not saying he is a puppet, but the powers he will have are limited.”

Codogno, a former Italian treasury official who participated in EU councils, said the EU was deeply concerned about the new Italian government. “There are a lot of worries: it is the first country in the eurozone with a populist government,” he said.

If the government followed through on reports of a €100bn financial stimulus without describing how they intend to pay for it, Rome would have to ask for more flexibility from EU eurozone rules, he said.

“If that happens it is likely to lead to a very confrontational situation with Europe and the commission,” Codogno said. “If you have a government behaving like a maverick, financial markets can move and if they move a lot they can cause a crisis, they can enter into a situation where a shock in financial markets can occur again.”

Given Conte’s lack of political experience, analysts on Monday said decisions on key ministerial positions would probably reveal the government’s intentions.

Salvini, who is staunchly anti-migrant and has touted a plan of mass deportation for undocumented people, has been touted as a possible interior minister, with control of the country’s migration policies. Di Maio has been touted as labour minister.

“A lot of promises they’ve made are utterly unrealistic, and they will have to pick their priorities,” said the analyst and author Wolfango Piccoli.

The new government has also inherited some difficult problems, and will need to find €12.5bn euros in the budget to meet EU budgetary commitment. They will also have to agree a plan on Alitalia, including a possible partial nationalisation of the Italian airline, and will have to make staff decisions on a host of big public institutions, like the Rai broadcaster.

Piccoli predicted that one of the few agenda items that will hold the M5S and the League together will be their shared criticism of Brussels, which is likely to object to the incoming government on issues ranging from the budget, to migration, to its desire for stronger ties with Russia.

Conte, a law professor at the University of Florence, is Di Maio’s personal lawyer and the mastermind behind the anti-establishment party’s pledge to abolish more than 400 “useless laws” that it claims will cut bureaucracy and free up the economy.

He also said during the election campaign that Italy’s anti-corruption laws needed to be tightened and major school changes introduced.

The professor, originally from the southern region of Puglia, was previously aligned to the left before joining M5S.

The government programme, which includes plans for a flat rate of income tax and universal basic income, as well as a raft of hardline policies against illegal immigrants, was backed by 94% of M5S members in an online poll on Friday, with 91% of League voters also in support.

Mattarella will need to ratify the choice of prime minister, the proposed programme of policies and cabinet lineup before a government can be sworn in. It will then face a vote of confidence in both houses of parliament.

Between them, M5S and the League won more than 50% of the vote in an election in March. Support for the League has grown from 17% to 25% since then, according to the most recent opinion polls, while support for M5S is steady at 32%.