Moved to action by the massacre in Orlando, the Senate voted Monday evening on four different gun-control measures. All four failed.

Sifting through the roll calls, an odd subgroup emerged: senators who favored extensive new measures to prevent terrorists, real or suspected, from passing a federal background check and buying a gun—but who don’t favor extending background checks to all gun sales.

The first measure voted on by the Senate was authored by Republican Senator Chuck Grassley, and it called for more federal spending on federal background checks and encouraging more sharing of mental-health records for the purpose of evaluating gun purchases. It also commissioned a federal study on why there are so many mass shootings.

The second was authored by Senator Chris Murphy, who led last week’s 14-hour filibuster on the Senate floor about gun control. It resembled the post-Newtown legislation that would make federal background checks universal and would close loopholes for sales at gun shows or online.

The two other measures dealt with preventing suspected terrorists from passing a background check for gun purchases. One, by Senator Dianne Feinstein, would allow the US attorney general to block a gun sale to anyone who has been targeted by a federal terrorism investigation. That person could challenge their background-check failure after the fact. Another, by Senator John Cornyn, would allow the attorney general to block a purchase after he or she goes to court and proves the person has, or is likely to, commit an act of terrorism.

Both the Feinstein and Cornyn bills have serious critics. The American Civil Liberties Union opposes both for “relying on unfair and discriminatory watchlists or failing to provide meaningful due process.” Cornyn’s bill would be simply ineffective, many critics argue, because federal law requires gun purchases to go through within three days if a background-check decision isn’t made, leaving little time for full court proceedings.

Putting aside the potential problems with both bills, let’s assume that every senator who voted for either the Feinstein or Cornyn had a genuine interest in preventing terrorists from obtaining guns. Democrats tended to favor the Feinstein measure, with Republicans gravitating to Cornyn’s bill.

But 55 of those senators didn’t vote for Murphy’s measure making background checks universal: Every Republican except Senator Jeff Flake, along with Democrats Jon Tester and Joe Manchin, voted against universal background checks but for one of the two terrorism-related gun bills. (Flake voted against all of them.)

Only 60 percent of gun sales happen through federally licensed firearm dealers, and the other 40 percent of gun sales happen without any background check. They usually occur online—Craigslist is a big gun clearinghouse—or through newspaper classified ads or at gun shows.

Republican senators had many ostensible reasons for opposing universal background checks in early 2013 and again Monday, but they never made a substantive case that the background checks (1) are not universal now and (2) would not become universal under proposed Democratic legislation. Their objections often involved (imagined) fears of a federal registry of gun owners that could be used for nefarious purposes down the road, perhaps including confiscation. The Grassley legislation attempts to improve the background-check system, but does not make any attempt to make them universal.

So for the 55 senators who voted for either Cornyn’s or Feinstein’s measures but not Murphy’s, this is what they effectively said on Monday: They are concerned with suspected terrorists buying firearms, but they would prevent the sale only if the terrorist voluntarily submitted to a background check. This would be akin to creating additional screening procedures at the airport, but making TSA lines entirely optional. Either these senators are quite optimistic about suspected terrorists’ asking federal permission to own a gun, or perhaps they were never that concerned about it in the first place.