Governor Andrew Cuomo and Mayor Bill de Blasio are escalating their fight over a real estate tax break proposal the mayor is pushing in Albany. The governor says it is a give-away to the real estate industry. The mayor says it will create more affordable housing. The feud is highlighting the increasingly tense relationship between the state's most powerful Democrats. NY1's Grace Rauh filed this report.

Governor Andrew Cuomo and Mayor Bill de Blasio are not mincing any words.

"I believe the mayor's plan offers a sweetheart deal to large real estate developers," Cuomo said.

"Well I guess the governor is not interested in the facts and maybe he hasn't read the plan," said the mayor.

The Democratic politicians are fighting over the mayor's plan to amend a tax break for developers—known as 421a—that is set to expire in June. The mayor wants to offer a longer, 35-year tax break to encourage the real estate industry to build more affordable housing. 

The public feuding began last week and showed no sign of letting up on Sunday, as both marched in the Celebrate Israel parade up Fifth Avenue.

"If the governor is more interested in supporting special interests than in housing the people of New York City, I think a lot of people would be frustrated by that," said de Blasio.

The governor says he is concerned the mayor's plan would not create housing that is truly affordable, and he says developers who get these tax breaks need to be paying higher wages to construction workers. The mayor's plan does not mandate that developers pay more to builders.

"I don't support a plan that leaves out the workers," Cuomo said. 

"It is sacred to the people of New York City that we create more affordable housing because people are being priced out of the neighborhoods. I want that to be built with union labor but at a reduced rate that we can afford," de Blasio said.

The mayor was generally well received along the parade route, but he did encounter some protestors—construction workers upset his plan would not require developers to pay higher wages.  

"I thought de Blasio was for the working man and women in New York City and it doesn't look that way," 

The stakes are high for the mayor when it comes to this debate. He has pledged to build or preserve 200,000 units of affordable housing over a 10-year period. If he doesn't get this tax break plan through Albany, his agenda may be in jeopardy.

The clock is ticking. The legislative session ends June 17.