Jacob made the announcement on Twitter as he was being pressured on social media to join the ranks of other performers who dropped out in the wake of this week's tragic mass shooting at a Texas elementary school.
As we reported ... the first domino was "American Pie" singer Don McLean, who decided the day after the Uvalde school shooting, which claimed the lives of 19 students and 2 teachers, he would not perform on the NRA stage. Don said it would be disrespectful to perform.
Next, "Broken Lady" singer Larry Gatlin pulled out Thursday, saying he could not perform at an NRA event in good conscious, saying he supports the 2nd amendment but wants background checks for gun purchases.
Jacob was the last man standing after T. Graham Brown, Lee Greenwood and Larry Stewart followed suit ... and it appears the hammer came down Thursday, though there has yet to be official word from the NRA.