WASHINGTON — Todd Staples has some fighting words for President Obama in an ad he has run more than 50 times on his quest to win Tuesday’s Republican primary for lieutenant governor of Texas.

“You’re not a king, and Texans bow to no one,” Mr. Staples says, looking directly into the camera and addressing the president, before he is shown picking up a gun at a store, aiming it over a counter and vowing to “fight Obama’s liberal agenda.”

After running through a list of his conservative credentials, Mr. Staples, the Texas agriculture commissioner, ends on an equally aggressive note: “So, Mr. President, if you still want to mess with Texas, we’ve got a saying for you: Come and take it.”

In Texas, tough talk in political advertising is as ubiquitous as the two-step, but especially when it comes to this election cycle’s Republican primaries. In commercial after commercial, Republicans up and down the ballot are rallying around common villains — Mr. Obama and the federal government — and promising to “fight” and “stand up to” the president and his policies.