For instance, Rudy Guiliani.
Now, if you want to ask him about crime reduction, I think he has valid experience and success. And he did make Times Square safe for people from small town America who want to come to the greatest restaurant city on the continent and eat at Red Lobster.
But national security and national politics?
Let's take politics first. Yes, he certainly was successful in becoming mayor of our largest city. However, that is less a partisan contest than a personality based one. On the national scene, he was the accepted frontrunner for the Republican presidential nomination and lost due to the worst strategic decision of modern politics, not competing in Iowa and New Hampshire.
On security, here's his record:
1. Located his command and control center in a complex that had already been attacked by terrorists.
2. Did not assure his fire and police communications systems were compatible.
3. After September 11th, proposed his corrupt and incompetent police commissioner to be the first U.S. Secretary of Homeland Security