Rome Mayor Ignazio Marino resigned on Thursday following a scandal over his credit card expenses that has dented the image of Prime Minister Matteo Renzi's Democratic Party (PD).
Marino, a PD member, denied allegations that he used city money to wine and dine his family and friends in what has become known as the "Dinner-gate" affair, but he had become an electoral liability for Renzi.
He has offered to pay back all the 20,000 euros ($22,500) that he claimed on his official credit card.
"I am resigning," Marino said in a statement, defending his record in office and saying his attempts to build a better future for Rome had been met with "a furious reaction" from vested interests.
The scandal, one of several which have dogged Marino for months, comes as the city prepares for the Roman Catholic Holy Year that is expected to bring millions of visitors to Rome.
His resignation followed a heated meeting of the city government when it became clear he no longer had Renzi's confidence and had lost his majority on the council.
When Marino initially refused to step down, his closest allies in city hall said they were resigning and the PD threatened to present a no-confidence vote in its own mayor.
Renzi, who has seen his own ratings dragged down by the Rome scandals, is now expected to name a special commissioner to run the city until a mayoral election is held, probably next year.
Opinion polls suggest it might be won by the anti-establishment 5-Star Movement, now the most popular party among Romans sickened by years of graft and poor public services.
Marino, 60, a former liver surgeon turned centre-left politician, has seen his position weaken steadily since the end of 2014 when prosecutors denounced an entrenched network of corruption in the city known as the "Capital Mafia" scandal.
He is not implicated in the alleged collusion to rig public contracts involving politicians, businessmen and criminals, but several of his councillors were forced to resign.
Marino, who took office in 2013, has also been accused of failing to respond to the general decline of the rubbish-strewn city, with public transport falling apart at the seams.
The dinner receipts scandal appears petty by comparison, but Marino was already weak and isolated.
Under pressure from allegations that he had fiddled his expenses, he published receipts showing he had regularly claimed for meals at restaurants near his home on national holidays and at the weekend.
On one occasion he said he had dined out with the ambassador of Vietnam, who promptly denied the encounter. A Rome church organisation also denied that he had dined with its members as he put in his expense claim.
Another time, he said he had hosted a representative of the World Health Organization, but the restaurateur told La Repubblica newspaper that he had eaten alone with his wife.
In a defiant resignation letter Marino called the receipts scandal "a squalid and manipulated polemic." He said he was paying the price for taking on entrenched corruption and feared the city would now fall back into its bad old ways.
He also said he may withdraw his resignation in the 20 days before a commissioner is appointed. However, considering his political isolation there appears virtually no prospect of him being able to carry on.