A woman views the a Mitt Romney ad called 'The Breakup' on September 6, 2012 in Washngton, DC. - 

Tonight, President Obama and Governor Mitt Romney face off in their second presidential debate of this campaign season. While the press coverage won't cost the campaigns a dime, Romney and Obama are gearing up for a final ad blitz.

Alex Burns, reporter for Politico, says the final weeks of race will bo doubt see a flurry of ads from both sides, but particularly from the Romney campaign. "We are starting to see Romney really close that gap in force," says Burns. "Right now you are sort of starting to see Romney 'empty the bombay'; last week was the first week, where nationally, he outspent Obama on the air."

Kantar Media estimates more than $3 billion will be spent on political ads this year, compared to $2.5 billion in 2008. Super PAC money, unleashed by the Citizens United Supreme Court ruling that allows unlimited spending by corporations and special interest groups, makes up a large portion of the spending.

Swing states, such as Florida, Ohio, and Virginia, are predictably receiving the most attention in ad buys. More than $100 million has been spent so far in Florida, according to the Washington Post. Nevada has also received a lot of attention. The New York Times reports that voters in Las Vegas have been exposed to 73,000 ads so far, the most ever fpr a market in a single year.

Follow Jeremy Hobson at @jeremyhobson