Idaho’s Most Expensive Legislative Primary Pits Sen. Jim Guthrie Against Challenger David Worley in District 28

Half a Million Dollars and Counting

The Idaho Senate primary contest between incumbent Jim Guthrie and challenger David Worley in District 28 has surpassed $503,000 in combined spending, making it the costliest legislative primary matchup in the state this election cycle. The race spans a rural southeastern Idaho district that includes Preston, American Falls, and communities near Pocatello.

Political action committees have collectively reported more than $375,000 in spending on the race, while the two campaigns themselves have spent an additional $128,000 combined. The primary is scheduled for May 19.

Where the Money Is Going

Guthrie, a Republican from McCammon who is seeking a ninth term in the Idaho Legislature, has drawn strong support from business-aligned PACs. The Idaho Prosperity Fund PAC, tied to the Idaho Association of Commerce and Industry, has spent more than $72,000 backing his campaign. The Idaho Liberty PAC — which has received contributions from St. Luke’s Health System and Micron Technology — has invested a similar sum on his behalf. The WinAg PAC and the PAC for Public Lands have also declared support for Guthrie.

Of the more than $237,000 in PAC activity surrounding Guthrie’s campaign, roughly 89 percent has been spent in his favor. Two PACs financed with out-of-state dollars are working against him: Make Liberty Win, affiliated with Young Americans for Liberty, has reported more than $23,000 in opposition spending, and the Citizens Alliance of Idaho has spent a smaller amount against him.

On the other side of the ledger, Worley has drawn backing from those same opposition groups. The Citizens Alliance of Idaho and Make Liberty Win have reported combined support spending of roughly $20,000 for the challenger. The 36-18-1 PAC, funded by Rep. Jordan Redman, R-Coeur d’Alene, has spent nearly $23,000 in Worley’s corner. PACs backing Worley account for about half of the more than $137,000 in total PAC activity around his campaign — a notably more even split than Guthrie’s.

The Idaho Liberty PAC and Defend and Protect Idaho have each spent tens of thousands of dollars in opposition to Worley.

Constitutional Officers Weigh In

The race has attracted an unusual level of attention from Idaho’s top elected officials. Attorney General Raul Labrador has endorsed Worley, while a coalition of five other constitutional officers — Gov. Brad Little, Lt. Gov. Scott Bedke, Superintendent of Public Instruction Debbie Critchfield, Secretary of State Phil McGrane, and Controller Brandon Woolf — have aligned behind Guthrie.

The split reflects broader ideological fault lines within the Idaho Republican Party, where establishment and business-aligned conservatives have repeatedly clashed with a more libertarian-leaning wing in recent election cycles. Those tensions have also surfaced in other contested primaries this season, including a crowded field of GOP challengers targeting Gov. Little.

A Second Race Worth Watching

The second-most expensive legislative primary so far involves another Republican rematch in North Idaho: Sen. Jim Woodward versus Scott Herndon, both from Sagle. That race has generated roughly $268,000 in combined PAC and campaign spending.

Herndon, who has positioned himself to Woodward’s right and has campaigned on eliminating property taxes, has received independent expenditure support from Redman’s 36-18-1 PAC and the Idaho Summit PAC, for which Rep. Josh Tanner, R-Eagle, serves as treasurer. Woodward’s campaign has been backed by Defend and Protect Idaho and the PAC for Public Lands.

What’s Next

With the May 19 primary now days away, additional PAC filings and late campaign expenditures are expected before voters head to the polls. A fuller picture of total primary spending will not be available until campaign finance disclosures are filed in June.

The Guthrie-Worley contest is one of several high-stakes Republican primaries shaping the direction of the Idaho Legislature. Rep. Russ Fulcher is also facing two GOP opponents in next week’s congressional primary, adding to what has become one of the more financially active primary seasons in recent Idaho political history.