Primary Attacks in General Election Ads

Kevin Drum comments on the back and forth between Clinton and Obama, but then adds:

That said, though, I have a question. It occurred to me today that primary opponents attack each other all the time, and yet I don't remember ever seeing a general election ad taking advantage of that. Once the general election starts, nobody seems to think it's worthwhile trying to make hay out of old attacks.

I can think of several reasons why this is true, but before I commit those reasons to print I'd like to make sure that it actually is true. Anyone got any examples that come readily to mind? TV ads preferred, but debate references and stump speech sound bites would work too. If you can come up with any, leave 'em in comments.

Here are two examples. The first is an LBJ ad from 1964:



Transcript:

ANNOUNCER: Back in July in San Francisco, the Republicans held a convention. Remember him? He was there, Governor Rockefeller. Before the convention he said Barry Goldwater's positions can "spell disaster for the party and for the country." Or him, Governor Scranton. The day before the convention he Goldwaterism a "crazy quilt collection of absurd and dangerous positions." Or this man, Governor Romney. In June he said Goldwater's nomination would lead to the "suicidal destruction of the Republican Party." So even if you're a Republican with serious doubts about Barry Goldwater, you're in good company. Vote for President Johnson on November 3rd. The stakes are too high for you to stay home.

And here's a Nixon ad from 1972:

Transcript:

ANNOUNCER: The McGovern Defense Plan. He would cut the Marines by one third, the Air Force by one third. He'd cut Navy personnel by one fourth. He would cut interceptor planes by one half, the Navy fleet by one half, and carriers from sixteen to six. Senator Hubert Humphrey had this to say about the McGovern proposal: "It isn't just cutting into the fat. It isn't just cutting into manpower. It's cutting into the very security of this country."

[Background music: "Hail to the Chief".] President Nixon doesn't believe we should play games with our national security. He believes in a strong America, to negotiate for peace from strength.