1st candidate said:

"Build a fence all along the border with Mexico."
 

2nd candidate said:

"Build a second fence in parallel to the first."
 

3rd candidate said:

"Put a moat in between the fences."
 

4th candidate said:

"Add barbed wire on top of the fence(s)."
 

5th candidate said:

"Electrify the fence with high voltage and put signs on it."
 

6th candidate said:

"Just give them the Texas treatment."