Romney campaign makes major TV ad buy

Mitt Romney's campaign is reportedly buying $3.24 million in television airtime in seven key battleground states, its biggest media buy of the general election campaign so far.

A Republican source tells CNN the Romney campaign is buying airtime in Colorado, Iowa, Nevada, New Hampshire, North Carolina, Ohio and Virginia starting this week. A Romney spokeswoman did not immediately respond to a request for comment.

The ad buy comes just days before Romney kicks off a five-day bus tour of six key swing states. According to CNN, Romney is investing heavily in three of the states he's scheduled to visit beginning later this week, including Ohio (where the campaign has purchased $838,455 in air time), Iowa ($385,745) and New Hampshire ($77,500).

The latest ad buy brings Romney's total ad spending to less than $10 million since mid-May, when he launched his first general election campaign spot. By comparison, the Obama campaign has reserved nearly $30 million in ad time through July, including a nearly $14 million ad buy made Tuesday.