Six GOP senators just told Trump to undo his own Russia deal — and pointed him at the bill he signed three weeks earlier

On Tuesday, October 13, 2026, twelve lawmakers — six Republicans and six Democrats — wrote to President Trump asking him to \"withdraw from this agreement, rescind General License No. 135, and execute the authorities provided under the Lindsey O. Graham Sanctioning Russia and Iran Act of 2026.\" Senator Thom Tillis of North Carolina had already said on Sunday the deal \"may be illegal,\" and the Tuesday letter hardened the position into a signed, public rebuke. The lead Republican signatory is the same Thom Tillis; the list runs McConnell, Cornyn, Collins, Murkowski, Armstrong — a coalition heavy with the chamber's institutional Russia hawks.

The diesel deal sits on top of a sanctions architecture the same administration built in reverse chronological order. On September 18, 2026, Trump signed H.R. 5334 — the Lindsey O. Graham Sanctioning Russia and Iran Act of 2026 — a bill that mandates up to 500% tariffs on Russian-origin imports and gives the executive up-to-100% tariff authority on each of the top five importers of Russian crude and natural gas. Three weeks later, on October 9, the Treasury Department issued General License 135 authorizing Russian-origin diesel transactions through April 7, 2027. The October 13 letter calls that license the opposite of what the Act requires.

Underneath the Graham Act sits an older, harder one. The Ending Importation of Russian Oil Act of 2022 passed the Senate 100-0 and the House 413-9 — it bans Russian-origin energy products covered by Chapter 27 of the Harmonized Tariff Schedule, which includes diesel. Section 3 of that law requires the president to consult four named committees, file a written report at least 45 days before any certification, and certify that Russia has withdrawn from Ukraine, poses no immediate threat to NATO members, and recognizes Ukrainian sovereignty — none of which has occurred. Even if those conditions were met, the statute imposes a90-day waiting period before any import ban could terminate. According to legal scholar Kristen Eichensehr at the University of Virginia, those certifications cannot be made and the consultation/report steps were skipped.

The Big Three US independent refiners entered the diesel story already running at near-record profitability. Q2 2026 net income came in at $5.1B for Marathon Petroleum, $3.7B for Valero Energy, and $3.8B for Phillips 66 — each more than triple the year-ago quarter. Marathon Petroleum's Refining & Marketing margin hit $36.33/bbl in Q2 2026 versus $17.58/bbl a year earlier; Refining & Marketing adjusted EBITDA reached $6.7B versus $1.9B. Phillips 66's realized refining margin more than doubled sequentially to $24.08/bbl; Valero Energy reported Q2 refining segment income of $6.34B versus $3.28B a year earlier.

On the day the GOP letter landed, the three refiners pushed to fresh 52-week highs — Marathon Petroleum closed at $476.98 (+3.96%), Valero Energy at $456.46 (+4.69%), and Phillips 66 at $292.73 (+4.00%). The market is not yet pricing a deal collapse; it is pricing the still-tight crack environment. The October 13 letter simply makes a collapse more probable — and a higher-probability crack-spread floor into Q4 is the single most important earnings tailwind for these names.

Fortune reported on October 11, 2026 that for the first time on record, US 10-year Treasury yields are correlating more closely with diesel prices than with crude prices since May. The same report noted that the 10-year closed at 5.24% on October 13 with Brent at $104.72/bbl. Goldman Sachs estimated the 800,000 metric tons of Russian supply initially announced would compress wholesale diesel cracks by $1–$2/bbl on the Gulf Coast and in Europe. That is a tiny number relative to the multi-dollar swing diesel has already absorbed: the 3-2-1 crack spread hit $66.25/bbl for the week to October 2 — the highest monthly value since 2006 — and global diesel cracks crossed $100/bbl in 2026 for the first time, per RBN Energy.

The downstream side of the diesel flow is where the Graham Act's authority bites. China took roughly 50% of Russia's crude exports and India 37% between December 2022 and August 2026 per The Diplomat. China rejected the US tariff threat the day the House passed the bill (262-159) on September 16, but Indian state refiners — IOC, MRPL, HPCL-Mittal — and Reliance had already begun cutting Russian crude in late 2025. Sinopec resumed Russian crude purchases in March 2026 after a temporary US waiver, buying roughly ten cargoes. The Oct 13 letter tells the President to use the very tool he built to top Russia into pricing India and China out of Urals-grade barrels — which would tighten supply for everyone and re-tighten crack spreads in the US Gulf Coast and Northwest Europe.

Short term (now through year-end 2026), the catalyst calendar is dense. Valero Energy reports Q3 2026 earnings on October 22; Phillips 66 follows with Q3 commentary; Marathon Petroleum reports on November 3. Each call will test whether management reads the GOP letter as a real unwind threat or a political statement. The market will likely learn the answer when Trump responds — he has defended the deal as \"the right choice\" but the letter cites a bill he himself signed. The first refiner to break ranks with Trump's framing — by warning on Q4 diesel crack compression risk — gets the steepest drawdown; the one that calls the letter \"noise\" keeps the Q3 multiple.

Long term (2027 into 2028), the architecture is what matters. The Graham Act's five-year sunset on the new tariff authority (the underlying framework runs to 2031 for the Iran Sanctions Act extension) means the executive has discretionary leverage through 2031 but Congress has tightened the leash until 2030. Even if GL 135 survives, Section 112 requires a 500% duty on Russian-origin goods by October 19, 2026 — under that authority, Russian diesel flowing into US refineries is structurally expensive. Refiners who import heavy Russian-sourced feedstocks face a real cost wedge that favors domestic mid-continent and Canadian heavy-sour barrels. The political fracture on October 13 raises the probability that the Section 113 secondary tariff on India and China is invoked before year-end — which keeps Russia's seaborne crude narrower [Global 17% of oil tankers, 53% of Russia's seaborne crude] and the shadow-fleet discount compressed, and keeps the global diesel market structurally short.