Inundated with fierce opposition from across the political spectrum, Democrats who lead the New Jersey Legislature have abruptly shelved a controversial redistricting plan that critics say could bolster their power for decades.

Democratic leaders had scheduled a vote for Monday, the final legislative session of the year, at the Statehouse in Trenton.

But staring down the possibility the plan might not pass in the face of broad backlash, state Senate President Stephen Sweeney and state Assembly Speaker Craig Coughlin announced Saturday night they canceled the vote.

That makes it unlikely the proposed constitutional amendment will be placed before voters next year — at least in its current form.

Sweeney, D-Gloucester, and Coughlin, D-Middlesex, said lawmakers will now consider reworking the plan.

“This will give us the time and opportunity to review the input we have received from the public, our legislative colleagues and others to determine if any of these ideas would improve the proposal,” Sweeney said in a statement.

“Redistricting provides the foundation for the democratic process and it gives voice to voters," he added. "We will maintain an open mind as we continue to work on a proposal that best serves the electoral process and the values of our democracy.”

The proposal (SCR152/ACR205) would put a question on next November’s ballot asking voters to approve an amendment to the state constitution overhauling how New Jersey draws its legislative districts. Those are the areas represented by the elected members of the Legislature, the body that makes the state’s laws and passes the state budget.

But opposition has poured in from Republicans and Democrats — including Gov. Phil Murphy and former U.S. Attorney General Eric Holder — as well as nonpartisan academics, good-government advocates and left-leaning groups who typically support Democratic candidates.

They say the biggest problem is the amendment would write a partisan formula into the constitution that heavily favors Democrats, barring a massive idealogical shift in the largely blue state.

The amendment would require at least 10 of the state’s 40 districts be drawn within five points of the average statewide vote in statewide elections — for president, U.S. Senate, and governor — over the last decade.

That would likely benefit Democrats because there are 900,000 more registered Democrats than Republicans in the state, a Republican U.S. Senate candidate hasn’t been elected here since 1972, and a Republican presidential candidate hasn’t won here since 1988.

Opponents have also cried the measure was being rushed through during the holiday season.

A similar plan died in the Legislature in 2015 after similar backlash — though this time, the criticism has been more fervent, coming at a time when progressive activism is growing.

Sponsors say the goal is to make redistricting fairer, more transparent, and more reflective of the states' voters, who happen to lean Democratic right now. State Sen. Nicholas Scutari, D-Union, said there’s been too much “hysteria” from detractors who don’t understand the plan.

But about 100 opponents slammed the measure at two public hearings in Trenton this past Thursday. Only the sponsors testified in favor.

Meanwhile, media outlets across the country have written about the proposal and Holder, the attorney general under President Barack Obama, warned it threatens to undermine national Democrats’ efforts to battle Republican gerrymandering in other states.

Voters should choose their elected officials, not the other way around. The Legislature’s redistricting proposal is bad for our democracy, period. pic.twitter.com/65VjxoREnZ — Governor Phil Murphy (@GovMurphy) December 14, 2018

Privately, Assembly leaders believed the plan had enough votes to pass in their house. But with no Republican lawmakers on board, Democrats could afford to lose only five votes in their party in the Senate. And at least three Democratic senators announced they were opposed, while others were on the fence.

In an interview that aired Saturday on New York City public radio station WNYC, one prominent Democrat said the proposal’s passage wasn’t a “foregone conclusion.”

“There’s something in this bill to affront almost everybody,” state Senate Majority Leader Loretta Weinberg, D-Bergen, told the station. “That’s not always easy to do. But apparently, that’s what we managed to do.”

What happens next is uncertain. Democrats could still move forward with the plan next year, but they’d now need support from three-fifths of the Legislature to place it on the 2019 ballot. Absent significant changes, that doesn’t seem probable.

Otherwise, their next chance would be the 2020 ballot. And that’s also unlikely because it’s a presidential election year, when even more attention would be paid to the plan.

Saturday’s decision was a win for Murphy, a progressive Democrat who often clashes with the more moderate Democrats who control the Legislature.

It was also a victory for liberal groups aligned with the rookie governor — many of whom helped Democrats flip four U.S. House seats in November’s midterm elections.

Murphy commended lawmakers for pulling the vote.

“I’m grateful they heard the voices of so many within New Jersey and around the country who saw that the proposal would have made our legislature less representative and less accountable," the governor said in a statement.

The amendment would also change the makeup of the 11-member commission that draws the districts. Currently, the chairmen of the Democratic and Republican state parties choose five members apiece and the state Supreme Court’s chief justice chooses the final member.

This would increased the members to 13, with the Legislature’s four leaders picking eight, the Democratic and Republican chairmen picking only two apiece, and the justice picking the last one. It would also require lawmakers to be on the commission and two members of the public that represent that state’s “ethnic, gender and racial diversity."

Because the plan would strip strength away from Democratic State Party Chairman John Currie, a Murphy ally, critics see that as an effort by lawmakers to dilute the governor’s power.

But sponsors argue the new commission would give more power to elected officials and the public rather than non-elected party chairs.

Coughlin said Saturday the proposal seeks to make “fair improvements” to the state’s redistricting process. But, the Assembly speaker added, he appreciates the public’s comments.

“I want to integrate some of the valuable input received to help create a better measure and improve the redistricting process overall,” Coughlin said in a statement.

State Senate Minority Leader Tom Kean Jr., R-Union, called Saturday’s decision “a big win for the people of New Jersey" because the amendment would take away "one of the most important rights we have as Americans: the power to choose who represents us in the halls of government.”

“I hope that this time, the sponsors will work with nonpartisan election experts and legislators on both sides of the aisle, so we can craft a redistricting proposal that we can all be proud of," Kean added.

NJ Advance Media staff writer Jonathan D. Salant contributed to this report.

Brent Johnson may be reached at bjohnson@njadvancemedia.com. Follow him on Twitter @johnsb01. Find NJ.com Politics on Facebook.