Yesterday Dan Patrick, the Republican nominee for lieutenant-governor, released a new television ad arguing that the pragmatic approach to illegal immigration favored by his Democractic opponent, Leticia Van de Putte, has left Americans vulnerable “while ISIS terrorists threaten to cross our border and kill Americans.”

He’s referring, implicitly, to the United States’s southern border with Mexico, and Patrick is not the only Republican to be raising this specter. Last month Jason Chaffetz, a Republican from Utah, said that he “had reason to believe” that four terror suspects–not affiliated with ISIS, but affiliated with other terrorist organizations–had been apprehended in Texas on September 10th. Several days ago Duncan Hunter, a Republican representative from California, told Fox News host Greta van Susteren that “at least ten ISIS fighters have been caught coming across the border in Texas.” 

There are many substantive disagreements between Patrick and Van de Putte about illegal immigration and border security, and Patrick has been calling for a greater focus on border security for years, but since he dragged ISIS into it, let’s talk about that. Hypothetically speaking, an ISiS fighter could try to enter the United States by sneaking across the border into Texas, but the “evidence” cited in all three cases doesn’t stand up. In reality there is no evidence that any ISIS fighters have illegally entered Texas, and no evidence that any are even making a serious attempt to do so. 

Patrick’s ad, in a footnote, cites a story from August 29, called “Online posts show ISIS eyeing Mexican border, says law enforcement bulletin.” The story concerns a three-page bulletin from the Texas Department of Public Safety, called “ISIS Interest on the US Southern Border”, based on “a review of ISIS social media.” The title refers to supposed “interest” in Texas’s border, not its “threats” against the same, and even that, if you read the article, is probably overstating the case:

Social media account holders believed to be ISIS militants and propagandists have called for unspecified border operations, or they have sought to raise awareness that illegal entry through Mexico is a viable option,” states the law enforcement bulletin, which is not classified.

Hunter and Chaffetz, meanwhile, both maintained that their information came from mysterious anonymous sources within law enforcement. Hunter’s spokesman, Joe Kaspar, told BuzzFeed News that the ten ISIS fighters Hunter referred to included the four that Chaffetz mentioned, which was odd, because Chaffetz had said that the four people in question weren’t affiliated with ISIS, but with other “known terrorist organizations.” And then Hunter’s spokesman elaborated:

[Kasper] told BuzzFeed News Wednesday that they have evidence from reliable sources about “foreign nationals” being captured along the border. Kasper said those foreign nationals may not technically be ISIS fighters, but do have suspected terror group affiliations. Kasper did not identify his sources but said that Hunter’s office remains convinced that the lawmaker was correct.

Meanwhile, both federal and state officials have flatly rejected such claims. I wouldn’t take a government bureaucrat at face value either, but it’s relevant in this case because all of the people warning about ISIS fighters in Texas are basing their information on claims supposedly made by other government bureaucrats. In Patrick’s case, at least, the source is real (the DPS bulletin) but its meaning been exaggerated. Hunter and Chaffetz are effectively saying we shouldn’t take Homeland Security Secretary Jeh Johnson’s word for it, but we should take their anonymous sources’ word for it–even though, in light of what Hunter’s spokesman said, it’s not clear whether anonymous sources in question said much beyond the widely known fact that not all the people apprehended by the Border Patrol are Mexican nationals

In addition, there’s no plausible reason to think that this is one of those cases where the lack of evidence suggests conspiracy or suppression, rather than an actual lack of evidence of ISIS fighters trying to cross the border. In certain circles, both of the preceding points–the lack of evidence and the lack of logic–are being dismissed by some fearmongers on the basis that it’s better to be safe than sorry. They may be correct about that principle, and if so, we should all be concerned. If Texans focus undue energy on being infiltrated by ISIS, that necessarily limits the resources we can direct to fighting other threats–some of which, unlike this one, are actually serious issues on the border; some of which, unlike this one, are real.