A provision that would allow so-called leadership PACs to transfer unlimited funds to national party committees was added to an appropriations bill in the Senate earlier this week.

The amendment was attached on Tuesday to the Transportation, Treasury and Judiciary spending bill, which also funds the Federal Election Commission. The full Senate Appropriations Committee is considering the legislation this afternoon.

If enacted, the language would allow leadership political action committees to transfer an unlimited amount of funds to the national party committees. Like all other PACs, the leadership committees are currently subject to a $15,000 a year limit on the amount they can transfer to the national parties.

Leadership PACs, a relatively recent invention, allow federal candidates to raise federally-regulated hard dollars in addition to the $4,200 per-cycle limit they can raise per individual for their campaign committee.

A few years ago, they were used primarily by a handful of Members with leadership aspirations, but recently the committees have become more common and are now used by rank-and-file and junior lawmakers.

Money raised by leadership PACs cannot be spent directly by candidates’ campaign committees, as that would circumvent federal restrictions on how much a lawmaker can raise from one individual.

Reform groups worry that the provision inserted in the appropriations bill would allow a less direct circumvention, however, as it would expand an existing avenue for federal candidates to raise money outside from their re-election campaigns and then transfer that money to the national parties. The parties could then use that money to support the candidates’ re-election bids.

While it is unclear who introduced the measure on leadership PACs, in the report accompanying the subcommittee legislation, the change is justified as putting leadership PACs on par with other federal campaign committees, which are not restricted in the amount they can transfer to the national parties. The report also points out that the money would still be subject to federal hard-dollar limits. The subcommittee is chaired by Sen. Kit Bond (R-Mo.).