Democrats haven’t lost a presidential race in New Jersey since 1988 or a U.S. Senate race since 1972 – and now hope to leverage that success in federal elections into a long-term majority in the state Legislature through controversial changes to redistricting.

The Senate budget committee on Monday endorsed a constitutional amendment that would link the once-a-decade changes to boundaries of state legislative districts to the past decade’s results in statewide elections for president, U.S. Senate and governor.

Redistricting experts say Democrats have received about 55 percent of the vote in those races recently in New Jersey. Going forward, if the amendment is approved, that would mean that the 10 districts deemed competitive would not actually be 50/50 tossups but would actually have a vote share in statewide races of up to 60 percent in favor of Democrats.

“Whichever direction New Jersey leans, the way this bill is worded, it’s going to advantage the majority party,” said Will Adler, a statistician with the Princeton Gerrymandering Project.

“The minority party in 2021, based on the way the formula is calculated, would get no more than 37.5 percent of the seats by design under the formula,” said Ben Williams, the nonprofit's legal analyst and project coordinator.

“And that’s the base scenario,” Williams said. “If you increase the number of seats in the competitive zone, the number of Democratic seats goes up, the number of Republican seats goes down.”

Right now, Democrats hold 66 percent of the Legislature and Republicans hold 34 percent, the largest partisan majority in decades. And now it could last for decades longer, if the amendment makes the 2019 ballot and is approved by voters.

Helen Kioukis, a program association with the League of Women Voters of New Jersey, called the amendment a “hyperpartisan proposal” that is undemocratic.

“Language that promotes the manipulation of district lines to favor one party over another has no place in our state’s constitution,” Kioukis said.

Bill Ames, of Morris County, said the state constitution is “being trampled quite a bit” and that the proposal seeks to predetermine future election winners.

“I’m concerned about a presumption here that apportionment is solely about a territorial dispute between two major political parties,” Ames said.

David Pringle, of Clean Water Action, said “this is not what democracy is supposed to look like.”

“This doesn’t help faith in government. This creates additional distrust. It is very difficult to see this as anything other than a naked power grab,” Pringle said.

Assembly Speaker Craig Coughlin, D-Middlesex, said the proposal will be considered in the Assembly in the upcoming three weeks.

If it is approved by a majority of lawmakers this year and again in 2019, it will appear on the 2019 ballot – despite not having the support of Gov. Phil Murphy, who said he’s “a proud Democrat” but that the proposal is rushed and flawed.

“Most importantly, I’m the chief executive officer of the state, and I want to stand on behalf of good democracy, where everybody’s voice is heard, where we open up democracy and not find ways to shut it down,” Murphy said.

The plan would take away some of Murphy’s power to appoint redistricting commission members through the state party chairman.