Will new GOP attack ad doom Sen. Mary Landrieu?

The Republican-leaning Super PAC American Crossroads has released a very tough new ad that attacks Sen. Mary Landrieu (D) of Louisiana by portraying her as loyal to Washington, D.C., not the Pelican State.

Here’s the context: Senator Landrieu is locked in a close race for reelection. Control of the Senate might hinge on whether she wins or loses.

Last week the Washington Post broke the news that she doesn’t actually own a Louisiana home. She lists her parents’ house in New Orleans as her residence, instead.

The American Crossroads spot picks up from there and basically frames Landrieu as a lawmaker who literally represents Capitol Hill.

It starts with news reports that Landrieu pushed for a $2 million earmark for Washington schools. It continues with such stuff as a D.C. lobbyist praising her for “making Capitol Hill a better place to live,” and ends with outgoing D.C. Mayor Vincent Gray labeling Landrieu “the senator representing the District of Columbia until we become the 51st state.”

Overlaid on this are scenes of typical family life, presumably in Louisiana. The not-so-subtle message: The folks at home see her only through the distant lens of TV cameras as she does stuff for Washington voters who didn’t elect her in the first place.

The general consensus in the punditocracy is that the ad is a hammer blow.

“Wow, this is a brutal attack ad against Mary Landrieu,” tweeted Taegan Goddard, publisher of Political Wire.

The overall residency issue is something many D.C. folk think could scuttle her reelection. As of Monday, Landrieu tops the Roll Call list of the 10 most vulnerable incumbent senators.

But is this ad really going to hurt her that much? We ask because it’s showing only on the web at the moment. American Crossroads has yet to put money behind it to ensure a wide exposure.

Instead it’s presumably a tease, something to get the political world excited about. The theory may be that if it gets exposure through stories (yes, such as this one), maybe it will drive Landrieu’s numbers down.

But attack ads aren’t magic. Yes, they may work, but only at the margins, and only if repeated as part of a continual campaign.

Maybe now is a good time to repeat some of the relevant conclusions from George Washington University political scientist John Sides’ classic 2012 round-up of what we do and don’t know about political advertising, which appeared in two parts in the New York Times 538 data-based blog back prior to the 2012 vote:

1. Campaign ads matter more when candidates are unfamiliar. (That doesn’t hold in this case, does it?)

2. Campaign ads work when you can outspend the other person. (That may or may not occur in Louisiana this fall.)

3. Campaign ads matter, but only for a brief time. Their effect decays within days.

4, Negative ads work, or they don’t work. Nobody really knows. Go figure.

These are good truisms to keep in mind as the US political world rounds the Labor Day corner and the sprint to the 2014 mid-term elections begins. Oh, how’s Landrieu doing in the polls? Right now she is basically tied with her probable GOP challenger, Rep. Bill Cassidy.