More than two months after President Donald Trump's tentative ceasefire with Iran collapsed, gasoline prices remain elevated. With midterm elections approaching, the president has turned his focus to the problem, unveiling a series of measures he says will secure additional crude oil from Venezuela and exempt refineries from renewable fuel mandates. Most recently, he summoned refiners to the White House earlier this week to discuss lowering pump prices. The refiners departed without making public statements, and the White House did not release an attendee list.

In the months since the blockade of the Strait of Hormuz, the world has adapted by conserving oil and rerouting Middle East crude, but structural factors continue to prop up prices. The U.S. average gas price on Thursday stood at roughly $4.11 per gallon — more than 90 percent higher than at this point last year — with diesel even costlier.

The "crack spread," the price difference between crude oil and refined gasoline and diesel, surged to a historic high above $70 per barrel, a clear indication that the refined products market is severely strained while oil companies reap substantial profits. The largest U.S. refineries have run at nearly maximum capacity for several weeks — longer than at any point in recent memory — and have postponed routine maintenance to capitalize on the soaring prices. That strain reflects a longer-term trend: U.S. refining capacity has declined in recent years as several older plants have closed, and no major new refinery has been built in the United States since the 1970s, leaving the system with little slack to absorb shocks.

The president's frustration over fuel costs has been evident throughout the summer. "Based on a shortage, they're making too much money," Trump said at an Oval Office briefing last month. "They ought to give some of that back to the public, and they better cut the retail price, the consumer price."

The central reason prices remain high is insufficient refining capacity to convert available oil into gasoline. Many Middle East refineries shut down during the conflict, and Russian diesel refineries are offline due to Ukrainian drone attacks. The remaining refineries in North America and China are too small to fill the gap. Building new refining capacity is widely viewed within the industry as a multi-year, multibillion-dollar undertaking, which is why the shortfall cannot be closed quickly even at today's elevated margins.

Venezuela gambit

The Trump administration first turned to Venezuela, where it kidnapped leader Nicolas Maduro in January and announced a plan to revive the country's moribund oil industry. Venezuela holds the world's largest proven crude oil reserves, though much of it is heavy crude that requires specialized refining — a constraint that has long limited how quickly its output can reach global markets. Experts said after the Maduro raid that American companies would hesitate to tap Venezuela's oil reserves, but the administration has sought to make the country more attractive by easing sanctions and pressing interim leader Delcy Rodriguez to rewrite the country's oil laws.

Those efforts appear to be bearing fruit. The Pentagon announced last week that it would take a stake in North American Blue Energy Partners, a private Venezuelan company controlling roughly 20 percent of the country's reserves. The company plans to boost production at oil fields once drilled by China and Russia. Alejandro Betancourt, who heads the company, has been described as Trump's "viceroy" in Venezuela; earlier this year the Trump administration helped him avoid a Swiss arrest warrant. Chevron, the largest U.S. company operating in Venezuela, also announced Wednesday that it would double production there, signing an agreement with the Rodriguez government at the Miraflores Palace in Caracas.

"In general, the read is positive," said Ramón Andrade, an energy-focused lawyer and partner at the Caracas firm Ponte Andrade & Casanova. He said Venezuela's business community is optimistic about a sector revival, but cautioned on the Pentagon deal: "I think we need to look at what's actually going to be signed."

Even so, experts say there is no chance these moves will lower gasoline prices before — or even after — the midterms. For one, only a small number of U.S. refineries can process Venezuela's heavy crude, and those facilities are already running flat out to exploit high fuel prices.

"Everything that the Venezuelans could produce right now, I'm sure they're squeezing out," said Al Salazar, an analyst at energy firm Enverus Intelligence who studies oil and gas markets. "You could get incremental production out of there in six to twelve months, but what really is causing the gasoline and diesel price spike is the lack of refining capacity."

Scaling up production will also take years, if the Pentagon's legal agreement even survives that long. Final details remain unavailable, and some parties allege that ceding resource wealth to the United States would violate the Venezuelan constitution. The interim government has yet to face voters in an election. "You need that long runway to be able to develop this resource," said Salazar, who spent decades in the Canadian oil industry, which also produces heavy oil like Venezuela's.

Biofuel waivers

The administration's other major action this week may do somewhat more to restrain prices at the margins, though likely not enough for most consumers to notice. The Environmental Protection Agency ended its summer ethanol blending requirements early. Those rules mandate that refiners and fuel importers add ethanol to the nation's fuel supply to reduce gasoline-caused smog. The EPA also announced a series of waivers exempting a few dozen refineries nationwide from integrating biofuel into their diesel and gasoline products. The "renewable fuels standard" is intended to support farmers and cut greenhouse gas emissions, since biofuels do not warm the planet the way oil does, but many oil industry parties contend that ethanol use raises refiner costs. Roughly a third of the U.S. corn crop traditionally goes toward ethanol production, which is why the mandate has long been a flashpoint between agricultural states and the oil industry.

Several major lobbies opposed the waivers. Midwestern politicians and biofuel associations argued they would hurt farmers by reducing demand for the corn used to make ethanol, and even the American Petroleum Institute warned that sudden exemptions would create an unpredictable business environment for refineries. The two sides of the biofuel debate disagree over whether the exemptions will reduce gasoline prices. With crude oil prices still high, ethanol may in fact be a cheaper ingredient than oil, and it is unclear whether exempted refiners such as Marathon and Chevron will pass savings on to customers.

Even with the waivers, gasoline prices in many states remain $1.50 above their pre-Iran highs. The conflict's early months hinged on the Strait of Hormuz, but even if the strait reopened tomorrow, the gasoline market would stay tight — neither more oil from Venezuela nor cheaper inputs would free up refining capacity.

"I think it's going to have a tremendous impact; ultimately, prices are going to come down," Trump said at the Oval Office on Monday. "Will it happen before the election? I can't tell you that."

Persistently high prices are an ominous sign for Republicans heading into the midterms. According to a Politico analysis of elections since 1978, the president's party on average loses 25 more congressional seats in midterm elections that follow gas price spikes than in those that follow price declines.

Conditions could worsen further. About half of U.S. refining capacity sits on the Gulf of Mexico, squarely in the path of Atlantic hurricanes. Forecasters predict a quiet season, but the potential for a massive outage remains. Tropical Depression Edouard formed in the Gulf this week and passed over a Texas refinery complex before fizzling out ahead of becoming a major storm.

This article originally appeared in Grist at Grist is a nonprofit, independent media organization dedicated to reporting on climate change.