With most of the media coverage of the 2016 elections focused on the jockeying between potential candidates for the Oval Office, it’s easy to lose sight of the slew of congressional races that will be decided next year. Not so for the Service Employee’s International Union (SEIU), which has devoted precious off-year resources targeting four Republican swing-state senators up for re-election in 2016. While the ads can be viewed on the group’s YouTube page, the public will be left in the dark on the cost, date and company behind the ads thanks to the porous disclosure requirements of current campaign finance law.

The new slate of digital ads from SEIU’s Committee on Political Education, which Sunlight first spotted on its Ad Hawk tool, slam Republican efforts to strip funding for President Obama’s executive order on immigration out of the Homeland Security reauthorization bill. Funding for the DHS will expire on Feb. 27, but many Senate Republicans split with their House counterparts over a bill that would strip funding for the president’s executive action.

Each of the senators targeted in the ads will face a competitive re-election race in 2016. You can see the nearly identical ads in the links below:

• Ron Johnson, Wis.
• Mark Kirk, Ill.
• Rob Portman, Ohio
• Pat Toomey, Pa.

SEIU is one of the nation’s largest and most powerful unions at around two million members, and has made immigration reform a centerpiece of its political agenda.

Last cycle the group reported spending over $36 million on elections to the Federal Election Commission.

Because the new ads don’t tell viewers expressly to vote for or against a candidate, they aren’t considered “independent expenditures” by the FEC. It’s not hard to guess the SEIU’s stance on the senators targeted, but because the spots avoid certain certain “magic words,” they aren’t considered to be campaign ads and thus aren’t subject to detailed reporting requirements.

The Bipartisan Campaign Reform Act of 2002 took a stab at strengthening the reporting requirements for issue advertisers, but didn’t touch campaign internet advertising, which was much less prevalent then. Under the current reporting regime, spending on online issue ads is only disclosed in a political committee’s disbursements, filed weeks or months after the fact and lacking information about the candidate and race targeted and type of expenditure. Other groups, like nonprofit “social welfare organizations,” do not have to disclose this spending to the FEC at all.

BCRA’s internet blind spot gives moneyed political groups ample room to tee off on candidates with online ads, while avoiding disclosure.

Messages left for SEIU requesting more information on the ad buys and their cost were not immediately returned.