Italian Prime Minister Matteo Renzi met informally with President Sergio Mattarella for about an hour on Monday, a person close to the situation said, without adding further details on their conversation. The Italian premier announced Sunday he would tender his resignation to Mr. Mattarella later this afternoon, after the country voted “No” in a key constitutional referendum. Mr. Renzi is expected to chair his last cabinet meeting in the afternoon and then formally tender his resignation to the president. It will then be up to Mr. Mattarella to decide how to handle the government crisis. Italy’s president will probably opt for a caretaker government that would be charged with overseeing the drafting of a new electoral law and ferrying the country to new elections. To form such a government, Mr. Mattarella first will have to hold consultations with all the political parties, a process that can take a few days or more than a week, depending on the parties’ divisions and the strength of Mr. Renzi, who remains the head of Italy’s center-left Democratic Party, the single largest in Italy’s Parliament. Mr. Mattarella will then ask someone to try to form a new government. Likely candidates include Economy Minister Pier Carlo Padoan and Senate speaker Pietro Grasso. The person would then choose his team of ministers, take the oath of office and seek confidence votes in both chambers of parliament. The whole process could take 10 days to two weeks.