Tens of thousands of people have staged a protest march in Ecuador's largest city against President Rafael Correa's planned constitutional reforms.
Mr Nebot said the new constitution would be "a slavery document"
The demonstration in Guayaquil, about 420km (261 miles) from the capital, was led by the city's Mayor, Jaime Nebot.
Critics say the reforms will focus more power in the president's hands and this will frighten off foreign investors.
Mr Correa argues that his reforms will make Ecuador a more just society and tackle endemic political instability.
Carried on the shoulders of his supporters, Mr Nebot delivered a speech from a stage in Guayaquil's main street.
He rejected Mr Correa's plans for greater state control over the economy, saying the new constitution would be "a slavery document".
"I'm willing to give you the rest of my life, my life for Guayaquil, for an Ecuador without misery, for an Ecuador which employs, for a rebel and autonomous Guayaquil within the unity of an Ecuador that works," he said.
Mr Correa celebrated his first year in office with supporters in Guayaquil
But Mr Correa, 44, who made reforming the constitution a key part of his election campaign, enjoys widespread popular support.
Last year, nearly 80% of voters backed his call for an assembly that would bypass Congress and rewrite the constitution.
A draft document is expected to be put to a national referendum this July for approval.
His supporters held a demonstration on a similar scale in Guayaquil last week to celebrate the anniversary of his first year in office.