Odessa shooter got his weapon by using private sale loophole that Mitch McConnell refuses to close: report

The man who fatally shot seven people while wounding 25 more in Odessa, Texas over the weekend reportedly obtained his weapon by taking advantage of a key loophole that Republican lawmakers have steadfastly refused to close.

Law enforcement sources tell ABC News' Matt Gutman that the shooter bought his AR-15-style rifle through a private sale, which meant he did not have to undergo a federal background check.

Previously, law enforcement officials investigating the shooting said that the shooter had actually failed to pass a federal background check, although they did not elaborate on how he got his weapon.

Gun control advocates have long wanted to extend mandating federal background checks for all sales of weapons, including private sales at gun shows or sales between individuals. So far, however, Senate Majority Leader Mitch McConnell (R-KY) has not endorsed any specific measures to strengthen background checks or reduce the availability of deadly weapons.

While many individual states do require background checks for private gun sales, many conservative states, including Texas, do not.

House Democrats earlier this year passed legislation that closed the so-called "gun show loophole" by requiring background checks on all sales of firearms, but so far McConnell has refused to take it up.