New York City Mayor Bill de Blasio is proposing a tax increase on the city’s wealthiest residents to fund a massive upgrade of the city’s crumbling subway system.

De Blasio is set to outline the proposal at a news conference in Brooklyn on Monday, but his administration released general details of the plan on Sunday.

The mayor’s spokesman Eric Phillips said in a Twitter post the plan would affect 32,000 of “the city’s wealthiest.”

“Revenue will help fix the system for everyone & cut fares for 800k low-income New Yorkers,” Phillips posted about the plan.

Details of the proposal were first reported Sunday by The New York Times. De Blasio told the newspaper his plan would generate between $700 million and $800 million annually. More than $500 million of the tax revenue would go toward capital improvement costs for subways and buses and about $250 million would fund half-price MetroCards for eligible low-income New Yorkers.

The mayor’s plan would increase the city’s highest income tax rate to 4.4 percent, up from its current 3.9 percent, for married couples earning more than $1 million and for individuals making more than $500,000 annually, according to details of the plan released by his office.

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“Rather than sending the bill to working families, and subway and bus riders already feeling the pressure of rising fares and bad service, we are asking the wealthiest in our city to chip in a little extra to help move our transit system into the 21st century,” de Blasio, who is running for re-election, said in a statement released by his office Sunday.

An average of 5.6 million users ride the city’s subway system on weekdays, and 2 million ride city buses on weekdays, according to MTA data.

The mayor’s proposal comes as he and Gov. Andrew M. Cuomo disagree over who should shoulder the cost of upgrading the city’s failing subway system.

Cuomo has said the state and city should split the cost of a short-term $836 million emergency subway repair plan unveiled last month by the Metropolitan Transportation Authority. De Blasio has countered that the city has already committed $2.5 billion toward the state-run MTA’s capital plan.

Cuomo and his newly appointed MTA chairman Joseph Lhota, in separate statements issued Sunday, noted that de Blasio’s plan would require legislative approval that could take up to a year to obtain.

“The City should partner with us and match the State funding now so we can begin Chairman Lhota’s overhaul plan immediately and move forward,” Cuomo said in his statement. “We cannot ask New Yorkers to wait one year to start repairs.”

Lhota, who learned about the proposal from The New York Times, said in a statement the MTA needs “short-term emergency financing now.”

“There’s no question we need a long-term funding stream, but emergency train repairs can’t wait on what the State Legislature may or may not do next year,” Lhota said.

The plan requires the support of the Republican-led State Senate, which has already shot down similar attempts by de Blasio, including a “millionaire’s tax” on real estate purchases that would have raised money for affordable housing programs.

Senate GOP spokesman Scott Reif, in an email said: “With New York City sitting on a surplus that is north of $4 billion, the absolute last thing we should be talking about is raising taxes.”

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The mayor, who campaigned at a church in Corona, Queens, on Sunday before marching in the annual Ecuadorean Day Parade in Jackson Heights, did not answer questions about the proposal.

With Vincent Barone