Mayor Bill de Blasio took his battle against Gov. Andrew M. Cuomo to a friendly union audience Saturday, eliciting boos when he described resistance in Albany to his agenda on schools, taxes and housing.

The governor in recent days said there's too little time left in the legislative session a less than three weeks a to accomplish what de Blasio wants. De Blasio has rejected that argument as "an excuse on the governor's part."

"I've seen our governor move mountains a when he wants to," de Blasio told the spring conference of the United Federation of Teachers at a midtown Manhattan hotel, where union president Michael Mulgrew introduced him as "this union's best friend."

Cuomo and de Blasio have been playing to different union groups in their ongoing conflicts.

The 110,000-strong United Federation of Teachers has supported de Blasio during his 17 months in office, including now as he seeks to retain direct mayoral control of public schools.

De Blasio wants a permanent renewal. Cuomo and the Democratic-led Assembly have proposed three years and the GOP-controlled State Senate wants just one year.

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The mayor also has been in an escalating war of words with Cuomo over the balance of developers and union interests in legislation to promote the building of affordable housing.

Cuomo has come out against de Blasio's proposal to update the decades-old tax break for developers known as 421-a, citing the opposition of construction trade unions and the AFL-CIO.

De Blasio would ask the unions to accept less than the "prevailing wage" on affordable housing projects to hold down costs.

Cuomo says de Blasio's plan contains giveaways to business.

Cuomo is also siding with city police and fire unions over de Blasio in their efforts to bolster disability benefits for on-the-job injuries.

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A Cuomo spokeswoman, Melissa DeRosa, Saturday called de Blasio's 421-a plan "a step backwards" in a statement. She did not address his other remarks.

De Blasio said he would pitch his agenda "to the people," who he said would "make their voices heard in Albany."

"It's time for the governor to get the facts," de Blasio said. "It's time for him to stand up for the people of this city."