Jim Risch Favored at 93% to Win Idaho Senate in 2026

Idaho hasn't elected a Democratic U.S. Senator since Frank Church won reelection in 1974. That 52-year drought didn't end on May 19, and prediction markets are now pricing the likelihood it extends to 58 years at 93%.

Senator Jim Risch, 83, secured the Republican nomination with approximately 61% of the vote, dispatching three challengers who collectively failed to mount a serious threat to the three-term incumbent. On both Kalshi and Polymarket, the Republican Idaho Senate winner contract surged 41 percentage points in three days, from a period low of 52% to its current 93%. That move tells you everything about where the real uncertainty lived: not in the general election, but in the primary itself.

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Jim Risch Locks Up Idaho GOP Primary at 61%, and Effectively the Senate Seat With It

The May 19 primary was the only election that mattered. Risch collected roughly 33,168 votes, according to preliminary results from the Idaho Capital Sun. Joe Evans, a 57-year-old Army combat veteran and data analyst from Boise, finished second at 18%. Josh Roy, a 44-year-old pulp and paper engineer from Lewiston, took 16%. Denny LaVé, a 49-year-old ironworker from Worley, trailed at 4%.

None of the challengers had statewide name recognition or fundraising infrastructure. Risch's 61% wasn't a squeaker. It was a comfortable reaffirmation of an incumbent in a state where the Republican presidential nominee has won by more than 30 points in recent cycles. Idaho's partisan lean makes the primary functionally equivalent to the general election for statewide offices, and Risch's margin left no ambiguity about voter preference within his own party.

With the primary settled, the prediction market moved decisively. But the size of that move tells its own story about where uncertainty lived all along.

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Republican Idaho Senate Winner Market Jumps 41 Points to 93%, and What the Move Actually Measures

The pre-primary price of 52% looks puzzling in hindsight for a state this red. It wasn't pricing a competitive general election. It was pricing a bundle of uncertainties: Could Risch lose his own primary? Would his age become a disqualifying issue before November? Would a surprise challenger emerge from the right flank? The market treated each of these as live questions, and the combined weight held the contract near a coin flip.

The 41-point surge to 93% represents the systematic elimination of those questions. Risch won comfortably. He appeared on the ballot and campaigned actively. No health crisis materialized. The market didn't receive new information about the general election. It simply collapsed primary-related uncertainty into a resolved outcome, leaving only the thin tail risk of a November surprise.

For context, comparable red-state Senate markets in deep-red seats typically price Republican nominees between 90% and 97% after primaries conclude. Idaho's 93% sits within that band, suggesting the market is treating this race as near-certain while still hedging against non-zero risks.

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Tracking the Republican Idaho Senate Market From Primary Season to 93%

The chart reveals a market that spent weeks oscillating around 52% before executing a sharp, clean repricing in the 72 hours surrounding the primary result. There's no gradual drift upward, no incremental confidence-building. This is a binary information event: the primary happened, Risch won, and the market jumped.

The flatness of the pre-primary period is itself informative. It suggests traders weren't gradually becoming more confident in Risch. They were waiting for the result. Once it arrived, the repricing was immediate and decisive, the kind of step-function move you see when a market transitions from genuine uncertainty to resolved fact.

What remains is a 7% gap between certainty and the current price. That gap is not noise.

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The Strongest Case Against Risch: What Would Have to Go Wrong for the 7% to Hit

The 7% residual probability deserves a serious accounting rather than a dismissal. Three scenarios could plausibly deliver a non-Republican outcome.

Health and age. Risch is 83 and would be 89 at the end of a fourth term. The actuarial risk of a serious health event between now and November 3 is non-trivial for any octogenarian, regardless of current fitness. If Risch were unable to continue his campaign, Idaho law and party rules would determine a replacement process. While a replacement Republican nominee would likely still win, the uncertainty surrounding that process creates a narrow window where the seat could theoretically become competitive or where legal challenges could complicate the outcome.

A scandal or disqualifying event. This is the standard tail risk in any near-certain political market. No specific evidence suggests one is forthcoming, but markets correctly price the non-zero probability of unknown unknowns. A financial scandal, legal issue, or damaging revelation could theoretically shift the race, though Idaho's partisan lean would likely absorb all but the most extraordinary shock.

Democratic overperformance. David Roth, who leads the Democratic primary at approximately 64%, will face Risch alongside Libertarian Matt Loesby and independents Todd Achilles and Natalie Fleming. In a normal Idaho cycle, the Democratic nominee functions as a placeholder. Roth would need a national political environment so toxic to Republicans that even Idaho's 30-plus-point partisan advantage couldn't hold. Nothing in current polling or national mood suggests that environment exists.

The honest assessment: the 7% is almost entirely health risk and unknown-unknown insurance. The electoral path to a Democratic victory in Idaho remains closed by structural partisanship. For traders, the question isn't whether to buy at 93% but whether 93% already fully prices the actuarial and tail risks of an 83-year-old nominee running through November. The answer is probably yes. But "probably" is exactly what 7% means.