SAN ANTONIO — Republican presidential candidate Rick Santorum is still having fun with his Etch A Sketch.

Santorum waved the toy around during a Texas appearance Thursday and claimed it represents rival Mitt Romney's lack of conservative convictions.

On Wednesday, a top Romney aide compared the transition from the primary campaign to the general election to an Etch A Sketch doodle toy, saying "you can kind of shake it up and we start all over again."

Romney's opponents have seized on the remark to challenge his conservative credentials.

Santorum addressed employees of a San Antonio insurance company that serves military personnel and their families. He said Texas' May 29 primary will be key to deciding who wins the Republican presidential nomination.