But Carlos Mazon sparked fresh anger for the manner of his announcement, which triggered another round of recrimination within Spain's political class over the disaster.

"The reality is that today I am the focus of criticism, noise, hatred and tension," Mazon said in a televised address. "I can't go on anymore."

Mazon had for a year consistently rebuffed calls for his resignation after the October 29, 2024 catastrophe killed more than 230 people, swept away 130,000 vehicles and damaged thousands of homes.

His conservative-run regional administration -- primarily responsible for the emergency response under Spain's decentralised system -- sent an alert to residents' mobile phones when flooding had already started in some places.

The warning came more than 12 hours after the national weather agency had issued its highest alert level for torrential rains.

Mazon did not change his schedule, having a lengthy lunch with a journalist, and critics allege the regional delay in raising the alarm cost lives.

Mazon said he "should have had the political vision" to cancel his appointments and visit the affected areas on the day of the disaster.

"I know I made mistakes. I acknowledge them and I will live with them all my life," he added, asking for "forgiveness".

- 'Shameless' -

In the town of Aldaia, one of the worst-hit municipalities in the eastern region, 22-year-old student David Genoves told AFP Mazon should have quit much sooner.

Monday's announcement "was a manoeuvre, desperate, at the last minute. Also, I see it as him shifting the blame elsewhere", Genoves said.

Retiree Agustin Cordoba, 62, agreed that the resignation came too late. "In my life, I have known no politician or person who is so shameless," he said of Mazon.

Campaigners have regularly staged protests against Mazon that gathered tens of thousands of people, and polls showed a majority of Valencia residents wanted him out.

Last week, relatives of the victims shouted "murderer", "coward" and "get out" at Mazon when he arrived for a state memorial service for the victims.

Rosa Alvarez, who heads an association representing flood victims, credited pressure from the protests for Mazon's decision, telling Cadena SER radio: "His party didn't make him resign."

She told a later press conference in Madrid that the campaigners sought "prison for Mazon, obviously a trial is needed".

But Mazon will remain a lawmaker in Valencia's regional parliament, offering him protection from an ongoing criminal investigation into the handling of the floods.

The Socialists accused Mazon of "not taking on the appropriate legal responsibilities" by "sheltering" in the parliament, demanding early regional elections.

Around 1,000 people rallied in the city of Valencia on Monday evening demanding elections and targeting Mazon, an AFP journalist saw.

- 'Cynicism' -

He is expected to be replaced as the regional leader by another member of his conservative Popular Party (PP).

Mazon had repeatedly argued his administration did not have the necessary information from state-run bodies to be able to warn people sooner.

"None of them (mistakes) were due to political calculation or bad faith," he said on Monday, taking a swipe at the Socialist-led national government for not helping sooner.

Analysts had said Mazon had become a burden for the PP's national leader Alberto Nunez Feijoo, who had continued to back his ally.

"No national emergency depends on a single person. That idea is intolerably cynical, simplistic, typical of someone wanting to evade their own responsibilities," Feijoo said on Monday.