Romney’s strong fundraising and big spending suggest that he and allied groups might finally eliminate Obama’s advertising advantage.  But as of the week ending October 14, that has not happened. As the graph below indicates, advertising spending on behalf of Obama continues to outpace spending on behalf of Romney.  Obama and allies aired about 5,000 more television ads than Romney and allies last week.

Why is this happening?  One of the challenges facing Romney and Republican-affiliated super-PACs and 501c’s is that they are currently paying higher rates for advertising than Obama.  This reflects both campaign finance law, which allows candidates to pay lower rates than independent groups, as well as Romney’s decision to buy advertising time relatively late in the cycle.  

Here is what this means: across all the presidential general election advertising by candidates, parties, and groups, each pro-Obama ad has cost an average of $502 dollars.  But each pro-Romney ad has cost an average of $630.

This may also help to explain why Obama has retained an edge in most battleground states.  Here is how both campaigns were targeting their ads in the previous week:

Both Romney and Obama are pursuing largely the same targeting strategy, focusing on Florida, Ohio, and Virginia.  The next tier of states is Nevada, Colorado, Iowa, and—despite some reports to the contrary—North Carolina.  Obama’s spending has outpaced Romney’s most significantly in Nevada and Florida.  The Obama campaign’s focus on Florida is interesting and, ultimately, perhaps fruitless.  Of the 5 toss-up states on the Pollster map, Florida is currently the state where Obama has the smallest chance of winning.  Nate Silver also sees Florida as an unlikely tipping point in this election.

Is any of this advertising making a difference?  That is the ultimate question and one I will revisit.  For the moment, however, there is one study worth noting.  The consulting firm Evolving Strategies recently completed a large randomized experiment in which participants saw pro-Romney ads, pro-Obama ads, both, or neither.  On the whole, the Obama ads were more effective in persuading weak partisans and undecided voters—even when the Romney ads were shown alongside.  Their effect was particularly notable among women.

However, there was a potentially countervailing effect as well: these ads tend to increase the enthusiasm of Republican voters but not Democratic voters, which could translate into additional Republican turnout.  

I’ll be back next week to update these numbers.

John Sides is a professor of political science at George Washington University and a founding member of the Monkey Cage.