Napolitano, 89, was to serve his term as president until 2020.
Napolitano was elected president in 2006. In 2013, he agreed to a second term to resolve deadlocked parliamentary elections. However, he made it clear that he was not ruling out the possibility of an early resignation.
In his New Year's speech on December 31, 2014, Napolitano announced his decision to resign in the short term, citing his advanced age and health problems. He did not specify the intended date of his resignation.
On Tuesday, Italian Prime Minister Matteo Renzi said Napolitano would step down “within a few hours.” Italian media expected the president's resignation letter to be signed about 11:00 a.m. local time (10:00 GMT) Wednesday.
Following Napolitano’s resignation, Senate President Pietro Grasso will become acting Italian president. Within 15 days, Chamber of Deputies President Laura Boldrini will call a joint meeting of both houses of the Italian parliament to vote for the country's new president.
