AUSTIN – Kay Bailey Hutchison will launch the first broadcast ad of the hotly contested 2010 campaign for governor today.

Hutchison will air radio ads statewide in what her campaign calls a "significant buy."

Campaign aides wouldn't comment on the content of the ad, but it will air through November.

The campaign between Hutchison and fellow Republican Rick Perry is expected to result in a deluge of ads, particularly on television, though it's unclear when those will start.

At the same time, Hutchison is placing automated calls to potential Republican voters explaining her decision to stay in the Senate while running for governor against Rick Perry. Some supporters fear that her months-long internal debate over whether to resign made her look indecisive.

In the recorded call, Hutchison explains that it was important to stay in office to fight Democratic-backed health care legislation.

"As a lifelong conservative, I simply cannot walk away from that fight. It might make my run for governor tougher, but that's a risk I must take," she says.