The Senate is close to taking a big step towards cleaner elections by approving a bill that would force secret donors to come out of the shadows and identify themselves, a measure that Gov. Phil Murphy has promised to sign. The bill was set for a vote on Thursday before a last-minute delay, but is likely to win approval soon.

This one is a big deal. The long effort to contain political spending has effectively collapsed, thanks to court rulings that protect unlimited political donations to “independent” groups as a form of free speech. The best we can hope for now is to throw open the curtains and let some light in, so that we can at least see who is pulling the strings.

If the Senate approves it, the measure will go next to the Assembly, where Speaker Craig Coughlin plans to hold a caucus discussion Thursday. He supports the principle of disclosure, he says, but wants to take a hard look at the fine print and hear from his members before committing.

As it happens, the fine print does need one tweak. The bill requires disclosure retroactively to the start of 2018, a provision that is vulnerable to a legal challenge, given that donors to some of these political funds were promised anonymity. Legal concerns aside, is it reasonable to change the rules after the fact? How is that fair to donors who understandably expected privacy?

The concern driving this effort is focused on political funds run by political figures, like George Norcross, whose team uses a secret fund to raise and spend millions of dollars on elections of his allies. One of his funds played a key role in protecting Senate President Steve Sweeney in 2017, after the teachers’ union spent more than $5 million trying to dethrone him and replace him with a rabid Trump supporter. We still don’t know who supplied the millions of dollars that rescued Sweeney, D-Gloucester, who has the power to block any bill or appointment on his own.

The governor is compromised in the same way. He helped raise money for a dark money group that was founded by four of his senior aides shortly after the 2017 election and appeared in its advertisements. To call that an “independent” operation is absurd, even if it technically passes legal muster. Brendan Gill, Murphy’s campaign manager, promised to reveal the names of donors at the end of 2018, but broke that promise recently.

So, who is writing the big checks to these groups supporting Sweeney and Murphy? Public worker unions representing police and teachers, who are among the highest paid in the country? The companies that have received billions of dollars in tax breaks? The polluters or real estate developers who prowl the hallways of the capital?

We don’t know, and we need to find out. That ball is in Coughlin’s court now.

The bill is opposed by several grassroots groups, liberal and conservative, who feel they are caught in the crossfire as good governments groups like the Brennan Center and the Election Law Enforcement Commission push to clean up the political system. Amol Sinha, the director of the ACLU of New Jersey, worries that donors may be scared away if they know their names will be disclosed. That’s echoed by conservative groups like New Jersey Right to Life and Americans for Prosperity.

“We have a lot of high-level anonymous donors,” Sinha says. “We don’t want our donors’ free speech rights to be chilled.”

In California, Sinha said, disclosure rules revealed the names of donors to groups pressing for marriage equality, one of whom worked for the Catholic Church. Wouldn’t that donor’s right to engage be infringed if his political activity could cost him his job, Sinha asks?

It’s a reasonable concern, but it’s outweighed by the need to protect our political system from the corrupting influence of dark money. We already reveal the names of those contributing directly to a political party, or to a candidate. Should those names be hidden as well?

In a democracy, we all have to be prepared to stand up for what we believe, to take a few lumps from those who disagree. If someone is fired or evicted for exercising their right to engage in politics, they can seek remedy in the courts, or by appealing to public opinion.

What we cannot do is allow wealthy special interests to have their way, to corrupt our democracy from the shadows. This bill will at least expose them, and the politicians who serve them. We are almost there. The next few weeks could prove to be critical to that effort.