Post-Convention Ad Crush to Get Even Heavier

Get ready, presidential swing states. Now the campaign ad crush really begins.

Spending on the TV ad war is expected to swell to $1.1 billion. The Kantar/Campaign Media Analysis Group, which tracks campaign ad spending, says that just over a third of that amount has been spent so far.

That means the campaigns and independent groups will spend more on the air in the final eight weeks of the presidential contest than they did in the first five months.

The biggest change is on the Republican side, with Mitt Romney now free to tap millions in general election funds he had collected but could not spend until becoming the party's official nominee.

Only eight states are considered true battlegrounds: Colorado, Florida, Iowa, Nevada, New Hampshire, North Carolina, Ohio and Virginia.