MADISON, Wis. (AP) — A super PAC backing Wisconsin Gov. Scott Walker's run for the White House announced a $9.25 million ad buy Wednesday for three early voting states, expanding on a $7 million television ad campaign that starts in Iowa next week.

The ad buy announced by officials with the Unintimidated PAC comes as Walker tries to right his campaign after shooting to the top of the Republican field in Iowa earlier this year, only to plummet in recent polls as billionaire investor Donald Trump and neurosurgeon Ben Carson gained momentum.

The new ad purchase includes $8 million in South Carolina, $725,000 in New Hampshire and $400,000 in Nevada.

The Unintimidated PAC, run by two of Walker's former top advisers who managed his three successful runs for governor the past four years, announced that it raised $20 million in the first half of this year.

News of Walker's ad buys comes just two weeks after the heavily funded super PAC backing his GOP rival Jeb Bush announced it was spending at least $10 million in Iowa, New Hampshire and South Carolina as well.

While Walker's Iowa ad campaign begins next week and runs until the Feb. 1 caucuses, the effort in the other three states won't begin until later this year or early next year. The ads backing Bush all begin this month and run through the end of the year.

The South Carolina ads backing Walker will appear in all major broadcast television markets, as well as cable news and the top 10 cable networks, beginning Nov. 7 and running through the Feb. 20 primary, an adviser with the Unintimidated PAC said.

The New Hampshire ads are reserved for the week before the Feb. 9 primary. Walker plans to ride his Harley-Davidson motorcycle around New Hampshire on Sunday and Monday.

The Nevada ads will run the week before the Feb. 23 caucus on broadcast and cable networks.

The idea of a parallel outside group that can raise unlimited sums from individuals, corporations and groups is not new. Mitt Romney, the 2012 GOP nominee, attempted it later in his campaign. Other Republican candidates in addition to Bush and Walker have super PACs backing them as well.

___

Follow Scott Bauer on Twitter at https://twitter.com/sbauerAP