Wachovia Corp., which is struggling to right its banking franchise, is betting heavily on marketing via radio.

For the week ending July 28, Wachovia was the seventh-most-active radio advertiser in the nation, running nearly 18,000 placements during that week alone, according to MediaGuide.com. That compares to just 336 radio plays during the week ending July 21. In all, 1.1% of all radio ad plays in the nation during the week of July 28 came from Wachovia. Put another way, Wachovia increased its radio advertising 5,166% during the week of July 28.

Wachovia is currently engaged in a major search for a new advertising agency. Currently, seven agencies are being considered, according to AdWeek..

Wachovia spent about $145 million on “major measured media” last year, according to TNS Media Intelligence. The Charlotte, N.C., bank has spent more on internet and radio ads in recent years and much less on network TV and newspaper ads. Between 2003 and 2007, network TV and newspaper spending fell 60% and 52%, respectively, at Wachovia, while internet and radio spending jumped 1,184% and 59%, respectively, TNS says.