Updated

A Republican senator is blocking a vote on the White House pick for Air Force chief of staff over the service's response to a widening sex scandal at a Texas base.

In a statement Friday, Sen. John Cornyn of Texas said he put a hold on the nomination of Gen. Mark Welsh, tapped to replace Gen. Norton Schwartz next month as the head of the Air Force.

"My hold on General Welsh will remain until I feel the Air Force is adequately addressing the unacceptable situation at Lackland and taking corrective steps to reform their training program to prevent this from happening again," Cornyn said.

Lackland Air Force Base in San Antonio is the site for basic training for all Air Force recruits. It has been rocked by scandal stemming from accusations of sexual assault.

One former instructor was sentenced to 20 years in prison by a military jury after he was convicted of rape and sexual assault. Military officials said this week the number of instructors under investigation total 15 and the number of alleged victims has increased by seven to 38.

Lackland has about 500 instructors for some 35,000 airmen who graduate every year. One in five recruits is female, while most instructors are male.

The Senate late Thursday approved several military nominations that had been cleared by the Senate Armed Services Committee on Wednesday but not the Welsh nomination.

The Hill, a Capitol Hill publication, first reported the Cornyn hold.