Sen. Cory Booker (D-N.J.) renewed his criticism on Sunday of former Vice President Joe Biden’s remarks on race, raising concerns that his 2020 rival’s words are “causing a lot of frustration and even pain” across the nation.

“This is a bad culture when you can’t admit mistakes, when you can’t speak to your vulnerabilities and your imperfections,” Booker told NBC’s “Meet the Press.” “We all have them, but when it comes to difficult issues with race, if you can’t talk openly and honestly about your own development on these issues, I think it’s very hard to lead our country forward so that we can actually deal with our past and rise to a better common cause and common future.”

Earlier this month, Biden lamented the collapse of bipartisanship in Washington, harkening back to his work with segregationist lawmakers during his time in the Senate.

During Thursday’s Democratic primary debate in Miami, Sen. Kamala Harris (D-Calif.) rebuked Biden’s comments and his stance against busing programs to integrate schools. The clash between the two candidates became one of the most talked about moments of the night.