Wichita (ap) — Political advocacy groups are playing an outsized role in the race for south-central Kansas congressional seat, campaign filings released Tuesday show.

Former congressman Todd Tiahrt has raised nearly $125,000 since announcing in late May that he would challenge U.S. Rep. Mike Pompeo for the 4th District House seat. Pompeo had more than $2.1 million in campaign cash at that time. He hasn’t released his latest finance report, but his campaign said it would do so late Tuesday.

“You can’t have a David without a Goliath — and all that money is a Goliath and I am representing the people,” Tiahrt said. “This needs to be about public service, it can’t be about power and money.”

Tiahrt’s campaign finance report also shows he loaned his campaign $51,000 and raised more than $90,000 from individual contributions. He also noted that 96 percent of the campaign cash Pompeo reported in his first-quarter finance report came from outside Kansas.

But the finance reports only show part of the money spent on the 4th District GOP primary race in Kansas, which pits Pompeo against Tiahrt, a popular conservative Republican who previously held that position for 16 years.

On Tiahrt’s side is Kansans for Responsible Government, a super PAC that’s free from campaign contribution limits because it independently advocates for his election that was formed by Kansas oilman Willis “Wink” Hartman, whom Pompeo beat in the 2010 GOP primary.

The group can’t give money directly to Tiahrt — who has criticized Pompeo for pursuing special interest agendas while not doing enough to help a local economy that is losing jobs — but filings show it has spent more than $162,000 so far this campaign on ads.

Meanwhile, a conservative group with ties to billionaire industrialists Charles and David Koch is spending big money to thank Pompeo for his work in Congress amid a bitter race this year for his seat. Pompeo was swept into office with the Tea Party in 2010, and says he’s now on a mission to reduce the size and scope of government.

The Kansas chapter of Americans for Prosperity is spending $409,225 for pro-Pompeo radio and television ads that begin Tuesday and run until the day before the Aug. 5 Republican primary.

“We like to be appreciative of those who share our values,” AFP state director Jeff Glendening said.

Tiahrt said he is confident his grassroots campaign will overcome AFP’s new advertising campaign and Pompeo’s fiscal advantage.

“He had $2 million to start with and I had zero, and that is not enough? I mean, that is obscene — to spend almost $3 million against someone who had zero dollars,” Tiahrt said. “… If he can’t manage his campaign on $2 million, he doesn’t deserve to be in Congress.”