Mayor Bill de Blasio used Manhattan's tallest residential tower as a backdrop to pitch his plan for a mansion tax on Thursday.

Standing in front of the 1,400-foot-tall, luxury condo tower at 432 Park Ave., de Blasio urged the New York State legislature to pass his 2.5% marginal tax on homes purchased for $2M or more.

De Blasio said if the tax passed, the city would collect enough from 432 Park Ave. alone to assist 2,000 low-income seniors in paying their rents through the state Elderly Rental Assistance Program.

“We’re in a housing crisis, pushing seniors out of their neighborhoods," de Blasio said. "We can’t afford more missed opportunities like this."

Proceeds of the tax from sales of 62 of the luxury tower's most expensive condos since December 2015 would amount to $30.2M, according to a release from the mayor's office.

In total, the Elderly Rental Assistance Program would raise $336M annually — an amount that would give 25,000 seniors up to $1,300/month in rental assistance.

Prospects for the mansion tax passing appear grim, Gotham Gazette reports, because Gov. Andrew Cuomo and Senate Majority Leader John Flanagan oppose the tax citing fears that it would cause the wealthiest New Yorkers to leave the city.

The CIM Group and Macklowe Properties developed the Rafael Viñoly-designed tower at 432 Park Ave., already home to several billionaires.

Saudi billionaire Fawaz Al Hokair purchased a penthouse condo last September for $87.7M. This week, Hong Kong-based CEO of Melco International Lawrence Ho purchased an 83rd-floor unit in the building for $65M, and former Citadel hedge fund manager Patrik Edsparr purchased a $33M condo on the building's 87th floor in late 2016.