Michael Waltz, a Republican candidate for the U.S. House of Representatives in Florida, declined to co-host a rally with President Donald Trump out of a concern for his unpredictable behavior, according to a Thursday Politico report.

Waltz is running in a usually solid Republican district, but is facing a robust Democratic challenger named Nancy Soderberg.

“District 6 is a safe Republican district,” pollster Brad Coker told Politico. “Why risk it? The problem with Trump is you never know what’s going to come out of his mouth.”