Gov. Phil Murphy said Friday that New Jersey will join with New York and Connecticut to challenge the constitutionality of a $10,000 federal cap on how much you can deduct in property taxes and state taxes.

Murphy said he signed an agreement with fellow Democratic governors in the tri-state area as a first step to filing a federal action against the new tax law, which will disproportionately raise taxes on wealthy blue state residents.

Gov. Andrew Cuomo of New York said on a conference call with reporters he didn't expect the lawsuit would be filed for several weeks as they work to recruit more Democratic-run states to join the cause and nail down their legal claims.

Murphy said on the call the provision limiting the state and local tax deduction was a "politically motivated" attack on blue states by a hostile Donald Trump administration. Most of the affected states send billions of dollars more to Washington then they receive back in federal services.

"I pledge that our administration is going to explore every legal mechanism to fight for our taxpayers," Murphy said. "We believe substantively there's a very strong case."

The average New Jerseyan deducts $21,720 in state and local taxes, more than double the shrunken deduction.

Governors from New Jersey, New York and Connecticut said the Republican tax law unlawfully targets a class of people, in this case residents of 12 high-tax states.

The Democrats said they expect to find though the discovery process communications and evidence of a politically motivated scheme to punish blue states.

They do not "coincidentally all happen to be Democratic states. Coincidentally have virtually no representation in the United States Senate. Coincidentally have only a small minority of house members. Coincidentally are states that President Trump lost in the last election," Cuomo said.

The governors said they're still exploring the nature of the legal challenge, but they may argue the law interferes with states' rights under the 10th Amendment and equal protection under the 14th Amendment.

They've also not yet determined in which court they'll file the action, though Connecticut Gov. Dannel Malloy said he expects it to land in the Northeast.

"We'll choose the best and most appropriate venue when the time comes," he said.

Murphy said joining the action doesn't preclude New Jersey from looking for other ways to counteract the tax law.

He's spoken in support of allowing local governments to construct support funds that would allow taxpayers to classify their property tax payments as donations that are fully deductible, and he said he's taken interest in a proposal made by Cuomo to shift from personal income taxes to payroll taxes, which can be deducted fully.

Samantha Marcus may be reached at smarcus@njadvancemedia.com. Follow her on Twitter @samanthamarcus. Find NJ.com Politics on Facebook.