ROME, Feb. 13 -- Italy's Prime Minister Enrico Letta announced on Thursday that he would resign over the next 24 hours, after his own Democratic Party (PD) and major force in the ruling coalition asked for a new cabinet to be formed.

The announcement arrived after PD leadership committee passed a document calling for a change of government, officially withdrawing its support to Letta.

The document passed with 136 votes in favor and 16 against. Only the closest supporters of Letta left the meeting and did not take part in the vote.

"After the decision taken by the Democratic Party, I have informed the President of Republic I will be going to him tomorrow to resign,"Letta said in a brief statement released in late afternoon.

His words marked the end of a very tense day, during which the PD leadership group had gathered in Rome to decide whether the party should keep supporting the current cabinet or not.

Under the new leadership of the 39-year-old Matteo Renzi, elected in December, the party has come to increasingly criticise the cabinet for the slow pace in implementing reforms and the poor results the government was able to produce in its 10 months of work.

Enrico Letta was appointed in April last year, two-month after inconclusive elections, to lead a fragile left-right coalition. He defended proudly what good achievements his cabinet was able to produce, explaining that he was forced to work amid persistent tensions and under the "most difficult circumstances."

Letta also answered to criticism by unveiling a broader reform agenda on Wednesday, and by asking political forces to give to his government time enough to implement all measures.

All attempts to solve the confrontation failed, however, and Letta did not take part in the PD meeting on Thursday, in order to leave his party's fellows "free to take their decision with serenity", as he wrote in a statement early Thursday.

After Letta officially resigns, President Giorgio Napolitano is due to begin a first round of consultations among political forces to verify whether a majority in support of a new cabinet is possible.

As leader of the largest party in Parliament, Renzi is seen as the most likely choice for the role of appointed new premier.

Early elections are not seen as a feasible choice at the moment, since the current electoral law was partially overturned by the Supreme Court and has been blamed for producing unstable majorities in Parliament. Going to the polls before a reform, according to analysts, would likely produce another inconclusive result.