The nomination of Giuseppe Conte, a political newcomer, to serve as prime minister of the incoming populist government of Italy appears to be hanging in the balance after questions arose about whether he padded his academic resume.

The controversy over the nomination of Conte, a law professor who claimed on a resume to have “refined” his jurist education at New York University, despite there being no record of him studying there, raises the possibility that Luigi Di Maio, the head of the populist Five Star Movement (M5S), could be back in contention to become Italy’s next premier.

Di Maio and Matteo Salvini, the anti-immigrant head of the League, who have agreed a shared agenda and have been trying since elections on 4 March to create a government, agreed days ago to take themselves out of contention to lead Italy and had settled on Conte, a virtually unknown candidate, to serve as premier.

The New York Times reported that NYU had no record of Conte ever attending the university as a student or as a professor, despite claims on his CV that he “refined” his studies there in 2008 and 2009.

Italy’s president, Sergio Mattarella, who can confirm or reject the choice of Conte, is seeking more time to consider the nomination. The delay led to speculation in Italian newspapers that Mattarella might push for Di Maio to serve in the role.

Mattarella has also expressed concerns over Di Maio and Salvini’s nomination of Paolo Savona, an 82-year-old Eurosceptic, to serve as finance minister.

If Conte is dropped it would represent the first major defeat of the potential new government and would be likely to feed allegations by the two populist parties that efforts to bring about change are being hampered by the foreign press and by Italian institutions.

As well as the NYU claim, Conte stated in his resume that he had enhanced his legal studies at Yale University in New Haven, Duquesne University in Pittsburgh, the Sorbonne in Paris and Cambridge University in the UK. Citing confidentiality rules, Cambridge said it could not immediately confirm or deny whether Conte had attended the university.

A university source later told Reuters they had not found any trace of a visit, but said the professor might have attended a course prepared by a third party.

The International Kultur Institut in Vienna is also named on the resume. Conte said he had worked on his legal studies there, but the Kultur Institut is a language school, according to an online profile.

The M5S defended Conte on Tuesday and criticised the foreign and Italian press for suggesting he had lied about academic credentials he had never claimed he have. “Giuseppe Conte wrote with clarity that he perfected and updated his studies at New York University. But he did not cite courses or say he completed a master’s at the university,” it said in a statement.

“Conte, like any scholar, has studied abroad, enriched his knowledge and perfected his legal English. For a professor of his level, the opposite would have been strange. He did it and rightly wrote it in the [CV], but paradoxically this is not good now and it even becomes a fault. It is the umpteenth confirmation that they [the press] are so afraid of this government of change.”

It is not the only controversy to emerge about Conte. News reports have highlighted his involvement in a case involving a now discredited medical treatment invented by Davide Vannoni, a former professor who in 2015 was convicted of conspiracy and fraud for administering unproven stem cell treatments to patients at his Stamina Foundation.

In 2013, Conte represented the parents of a child suffering from metachromatic leukodystrophy, a degenerative disease that leads to paralysis and blindness, in their fight to get their daughter access to the treatment. After he won the case, the child, Sofia De Barros, was treated with Vannoni’s Stamina method at a hospital in Brescia. She died in December 2017.

The Italian government banned testing for the method in 2014 despite intense pressure from pro-Stamina activists, among them Beppe Grillo, the comedian who founded the Five Star Movement.

The question now is whether the controversies over Conte will allow Di Maio ? a politician the head of Italy’s biggest party ? to become prime minister. Both he and Salvini were frequent critics of previous prime ministers such as Matteo Renzi who were not directly elected.