ATLANTIC CITY, N.J. (AP) — With New Jersey GOP Gov. Chris Christie handing power to Democrat Phil Murphy come January, the state's Democratic leaders, at a convention on Wednesday, cast congressional Republicans and President Donald Trump's tax overhaul plan as a top obstacle in the coming year.

Democratic Senate President Steve Sweeney and incoming Assembly Speaker Craig Coughlin — along with their GOP counterparts — addressed the state's annual local government conference in Atlantic City, offering a stern warning about the potential fallout for Republicans if a proposed tax overhaul goes forward.

"What I saw was a warning shot across the bow to the Republicans," Sweeney said. "These tax (changes) they're talking about are gonna devastate the state. If I'm a Republican I sure as hell wouldn't want to run next year."

The discussion comes as the Republican-led Congress considers a tax overhaul that includes eliminating state and local deductions. The House proposal leaves a property tax deduction of up to $10,000 in place, but a Senate plan scraps it entirely.

The plans could have a significant impact in New Jersey, since it has the country's highest property taxes. The state estimated that in 2016 the average property tax bill was about $8,500, but a number of towns exceed the proposed cap.

Coughlin said the GOP's support for the tax overhaul should be an "acid test" for the party.

"They're gonna have to decide who's side they're on. Whether they're gonna be on the side of partisan politics trying to support the president," he said. "Or whether they're gonna be on the side of New Jerseyans."

The discussion is an annual event that fills a large convention center hall and is closely watched for signs of what voters can expect from state government in the coming year.

This year's event carried added interest because next year will be the first time since 2009 that Democrats will control the state's government.

Murphy has promised a raft of new proposals that could also face criticism. Among his promises is fully funding school aid and the public pension. He's proposed financing it in part by raising income taxes on millionaires.

Republicans will hold less leverage next year. Unlike in Washington, for example, there are no supermajority requirements to end filibusters.

Assembly Republican Leader Jon Bramnick said the loss of dual-party control of government could be a bad thing for New Jersey, just as it's not going well for Trump and Republicans, who have seen their approval ratings crater.

"I'm a big fan of balance in government," he said. "Now I'm always concerned when one party controls any entity for too long."

Republicans often tried to cast this year's election in terms of checking Democratic control on state government, arguing that Christie was the only thing stopping taxes from going up, but voters seemed to reject the message.

Murphy beat Republican Lt. Gov. Kim Guadagno by more than 13 points. She was saddled with Christie's low approval ratings as a member of his Cabinet for two terms and faced headwinds because of Trump, who is not popular among many in the state.