N.Y. Democrats Vowed to Get Big Money Out of Politics. Will Big Money Interfere?

He dismissed the benefits that Democrats had accrued from the loophole in the past. “For better or for worse, people campaign under the laws as they are when they’re running,” he said. “There is a consensus among Democrats that we should change this law.”

Mr. Kink was also optimistic about the prospect of reform, adding that heightened voter attention to money in politics could be enough to dissuade lawmakers from reneging on their promises. Democrats especially, with their New York City base, could be wary of getting too cozy with the real estate interests most associated with the loophole, he said.

“You’ve got a bunch of lawmakers that might or might not care about abstract campaign finance or good government rules,” Mr. Kink said, “but they understand that taking care of tenants is really important to their political survival.”

The push coincides with a surge in attention nationwide to the once-humdrum issue of money in politics. New York City voters on Nov. 6 overwhelmingly approved a ballot proposal to lower contribution limits for city races and to increase the city’s matching-funds program for candidates. Baltimore and Denver also voted to introduce or expand matching-fund programs. A growing number of high-profile Democratic politicians, including Representative-elect Alexandria Ocasio-Cortez and United States Senator Kirsten E. Gillibrand, have pledged to reject corporate PAC money.

If the Democrats close the L.L.C. loophole and carry out other changes they have backed, including a statewide small-donor matching funds program, New York’s campaign finance laws could go from the nation’s most lax to its most robust, said Lawrence Norden, deputy director of the Democracy Program at New York University’s Brennan Center for Justice. No other state has a similar active matching program.

The timing of reform may prove pivotal to what is sure to be one of next year’s biggest legislative fights: renegotiation of the state’s rent laws, which are set to expire in June. If Democrats close the L.L.C. loophole early, developers may lose one powerful means for making their voices heard.

In the past, real estate groups used L.L.C.s to deluge upstate Republicans, knowing that their constituents would be less likely to care about the industry’s long shadow, according to Susan Lerner, the executive director of Common Cause New York, a government reform group.