Amid the end-of-year rush to finish the rest of its agenda, the Senate voted to restore a tax regulation that free speech advocates say enabled the Obama administration to unfairly target conservatives. The House has yet to vote on the resolution.

The vote was a narrow 50-49 margin. Sen. Susan Collins, R-Maine, voted with all 49 Democrats, and Sen. Thom Tillis, R-N.C., was absent.

The resolution nullifies a rule issued by the Department of the Treasury that would exempt certain nonprofit advocacy organizations “from the requirement to report the names and addresses of their contributors on returns filed with the Internal Revenue Service.”

After the vote, Senate Minority Leader Chuck Schumer, D-N.Y., said he was “proud” that Collins joined with all 49 Senate Democrats to stand against what he called “the Trump Administration’s attempt to shield mega-donors and their dark money influencing our elections from disclosure.”

However, opponents of the resolution like Judicial Watch President Tom Fitton say that the disclosure regulation enabled the IRS to target conservative and libertarian groups during the Obama Administration.

In July, Senate Majority Leader Mitch McConnell, R-Ky., called the IRS rule change “particularly welcome news to those of us who are intently focused on defending the First Amendment, for those of us who raised concerns during the last administration about activist regulators punishing free speech and free association.”

The Treasury Department has previously said that it doesn’t need to know the identity of donors to do its job effectively.

"Americans shouldn't be required to send the IRS information that it doesn't need to effectively enforce our tax laws,” Treasury Secretary Steve Mnuchin said of the change earlier this year, “and the IRS simply does not need tax returns with donor names and addresses to do its job in this area.”

The resolution still needs House approval to actually strike down the regulation, however, and it’s unlikely that will happen before the end of this Congress.