Story highlights Renzi gave his official resignation to the President on Wednesday evening

Almost 60% of Italians voted against Renzi's constitutional reforms

(CNN) Italian Prime Minister Matteo Renzi officially resigned Wednesday after a crushing defeat in a referendum on constitutional reform.

Sunday, Italians voted decisively against changes to the constitution put forward by Renzi, a vote that became a poll on the prime minister's leadership.

Renzi addressed his center-left Democratic Party Wednesday evening, giving a speech on his short term as prime minister that marked his government's achievements.

"I'm leaving this country with less taxes to pay and more rights, and our party should be proud of that," he said.

One of Renzi's hallmark pieces of legislation was the legal recognition of same-sex unions.

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