John Cornyn said he plans to support Ted Cruz for re-election in 2018.
Both the Texas Republican senators closed out the Texas Tribune Festival on Sunday on the UT campus.
The senior senator previously withheld his endorsement of his junior colleague.
Cornyn also said he will run for a fourth term in 2020.
Cruz also didn't endorse Cornyn in 2014.
The pair discussed Harvey relief, DACA and Colin Kaepernick, the former NFL football player who took a knee during the National Anthem.
"But I think that is disrespectful to the soldiers, and sailors and airmen and marines that are fighting to protect our rights and we have every bit of right to say I disagree with your speech, that's how free speech works," said Senator Ted Cruz.
"I think it is profoundly ungrateful given the sacrifice that our military personnel have made and their families and some of whom have made the ultimate sacrifice not to demonstrate respect for the flag," said Senator John Cornyn.
Cornyn said the pair has had differences in the past but now are standing together in light of Hurricane Harvey.