U.S. Sen. John Cornyn is making what some Rio Grande Valley lawmen say is a bogus claim about the status of border security.

I must stipulate that Cornyn is a Republican and the law enforcement officers are Democratic sheriffs. So, one must understand the politics involved.

Cornyn said recently that a South Texas rancher has told him that as many as 300 people are crossing the Rio Grande River illegally every night. He won’t identify the name of the individual making the claim, but does say he’s a friend of the senator’s. The Dallas Morning News, though, reports that sheriffs along the border scoff at Cornyn’s assertion, saying that such a mass migration across the border would produce 110,000 illegal crossings annually, which they say is more than double the estimated number of people estimated by the federal government who elude capture every year.

Zapata County Sheriff Alonzo Lopez, one of the Democratic lawmen who say Cornyn is making this stuff up, said: “We would be acting on that if it were true. We never hear about large amounts of people crossing ’cause it’s not happening.”

Sure enough, the sheriffs have their political turf to protect. They can’t acknowledge this kind of massive breach along the border for fear of creating election-year issues for opponents to use against them. However, Cornyn also has some worries awaiting him, particularly if the tea party wing of the GOP mounts a challenge against him in the 2014 Republican primary. Cornyn wouldn’t be the first member of either the Senate or the House to embellish something for political effect, to give himself a straw man to knock down just to demonstrate his toughness on a particular hot-button issue.

And the way Cornyn’s been acting in recent years, by swinging far to the right to avoid that kind of political ambush, it wouldn’t surprise me in the least to learn that he, too, is telling a tall tale.

Here’s an idea, senator: Tell the world who’s feeding you this intelligence and let that individual answer the questions directly.