# Will Marco Rubio defeat Gavin Newsom in the 2028 presidential election, with Gavin Newsom as the Democratic nominee and Marco Rubio as the Republican nominee

> Liquidity-weighted aggregate at 6% across 6 contracts — refreshed 3 min ago.

URL: https://simplefunctions.dev/odds/presoutcome
Updated: 2026-07-14T09:20:49.801Z
Category: politics · Topic: election-2026
Status: active
Closes: 2029-01-20

## Headline

- Probability: 6% (liquidity-weighted across 6 contracts)
- Venue: Kalshi (6 contracts)
- 24h volume: $34

## Bound contracts (6)

| Outcome | Price | 24h | Volume | Venue | Slug |
|---|---|---|---|---|---|
| Marco Rubio defeats Gavin Newsom | 11¢ | −1pp | $34 | kalshi | /markets/will-marco-rubio-defeat-gavin-newsom-in-the-2028-p-kalshi-kxpresoutcome-28nov07-gnewmrubr |
| Gavin Newsom defeats JD Vance | 6¢ | +1pp | $0 | kalshi | /markets/will-gavin-newsom-defeat-jd-vance-in-the-2028-pres-kalshi-kxpresoutcome-28nov07-gnewjvand |
| JD Vance defeats Gavin Newsom | 8¢ | −2pp | $0 | kalshi | /markets/will-jd-vance-defeat-gavin-newsom-in-the-2028-pres-kalshi-kxpresoutcome-28nov07-gnewjvanr |
| AOC defeats JD Vance | 4¢ | −1pp | $0 | kalshi | /markets/will-alexandria-ocasio-cortez-defeat-jd-vance-in-t-kalshi-kxpresoutcome-28nov07-aocjvand |
| AOC defeats Marco Rubio | 3¢ | — | $0 | kalshi | /markets/will-alexandria-ocasio-cortez-defeat-marco-rubio-i-kalshi-kxpresoutcome-28nov07-aocmrubd |
| Jon Ossoff defeats Marco Rubio | 4¢ | — | $0 | kalshi | /markets/will-jon-ossoff-defeat-marco-rubio-in-the-2028-pre-kalshi-kxpresoutcome-28nov07-jossmrubd |

## 30-day trajectory

| Day | Aggregate |
|---|---|
| 2026-06-14 | 7 |
| 2026-07-01 | 8 |
| 2026-07-07 | 8 |
| 2026-07-09 | 11 |

_19 days of price history captured. Each row is the daily mean of intraday 5-min captures._

## What moved the line

- 2026-07-08 · Marco Rubio defeats Gavin Newsom +5pp 8→13¢ · kalshi

## Analysis

This probability represents the chance that Marco Rubio defeats Gavin Newsom if both become their parties' 2028 presidential nominees. The 7% figure reflects market assessments that while Newsom securing the Democratic nomination is moderately plausible (24¢ implied probability), Rubio winning the general election against him is considered unlikely. The current level is driven by two main considerations: Newsom's relative strength in general-election matchups versus other potential Republican candidates, and historical patterns where incumbent-party nominees face headwinds after serving for extended periods. The biggest near-term catalyst will be the 2026 midterm results in November, which typically signal broader electoral trends and could shift perceptions of each candidate's viability. Additionally, any major economic data, foreign policy developments, or shifts in either candidate's political standing before the 2028 conventions would significantly alter these probabilities.

### Key factors

- Newsom's 24¢ nomination probability implies markets see him as a credible but not heavily favored Democratic candidate, requiring Rubio to clear higher odds in a general matchup
- Rubio's 23¢ Republican nomination probability suggests meaningful uncertainty about whether he secures the GOP nomination, directly capping the joint scenario's probability
- Historical data shows general-election matchup polls 2+ years before the election have limited predictive power, but current head-to-head metrics between these candidates would inform traders
- 2026 midterm performance will provide signals about national sentiment and either candidate's coattails, potentially shifting both nomination and general-election probabilities
- Economic conditions and incumbent approval ratings between now and November 2028 are major variables that typically determine general-election outcomes

## Methodology

Probability is **liquidity-weighted** across all bound Kalshi/Polymarket contracts: Σ(price × volume) ÷ Σ(volume). 30-day trajectory uses the daily mean of intraday 5-min captures. 24h delta = today's mean − yesterday's mean. Movement events are ≥3pp daily moves in the last 7 days.

## How to use this data

- HTML: https://simplefunctions.dev/odds/presoutcome
- JSON: https://simplefunctions.dev/api/public/odds?slug=presoutcome
- Topic hub: https://simplefunctions.dev/predictions/election-2026

## License

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