That brought objections from Kim Olson, a retired lieutenant colonel who is running against Miller in the Nov. 6 general election.
"This is not something I want to go to the mat for. I want to represent folks in agriculture," Olson told the Chronicle. "We have bigger fish to fry."
Miller said Monday that he saw nothing wrong with the plate and was not unconcerned if black Texans would be offended.
"The Confederate flag is one of the six flags that flew over the state," Miller told the Morning News. "There's no profit in hiding our history and trying to rewrite history."