The long-planned annual meeting -- hosted this year at Trump's Miami-area golf club -- kicks off over a week after he ordered strikes alongside Israel on Iran, prompting retaliatory attacks across the Middle East and sending ripple effects around the world.

As crude prices soar to multi-year highs -- with a corresponding spike in US fuel prices -- Republicans face potential blowback just eight months before the November vote.

Losing their narrow control of Congress could also derail the final two years of Trump's term in office.

The new open-ended conflict has already divided the president's base, after the 79-year-old business tycoon campaigned on ending overseas wars.

Marjorie Taylor Greene, a former close ally of Trump who resigned from Congress after publicly breaking with him, called the new Middle East conflict a "betrayal" of his populist "MAGA" movement.

Conservative podcaster Megyn Kelly has meanwhile voiced "serious doubts" about the operation.

In the halls of Congress, only a few Republican lawmakers have expressed concern over the conflict, but they could become more vocal over time if already negative public sentiment sours further.

"Usually, foreign policy doesn't play a big role in midterm elections...unless there is a direct connection to how it is making people's lives worse," Todd Belt, a political management professor at George Washington University, told AFP.

He warned that economic impacts from the soaring price of oil, which could linger until election day and add to the usual headwinds that the president's party faces in midterm elections.

When voters "see the cost of goods going up faster than their own wages, then they can make that connection, and that will have a negative ramification on whoever is in office, and now it's Donald Trump," he said.

- 'FOOLS' -

Trump and Republicans rode a wave of negative economic sentiment to success in the 2024 elections, but rising costs due to the war could see them in the firing line of voters.

Trump's administration has downplayed the economic impacts of the war, insisting any price hikes would be temporary.

After the price of crude oil shot above $100 a barrel for the first time in years on Sunday, Trump defended the war as a "very small price to pay" for peace and security.

"ONLY FOOLS WOULD THINK DIFFERENTLY!" he wrote on his Truth Social platform.

However, the message is unlikely to resonate with many in the United States, where gas-guzzling vehicles remain popular.

"Maybe it's just me...but seems not super smart to win an election on inflation and then start a war that causes oil prices to spike by 50% within like four days," data expert Nate Silver quipped on X.

According to Belt, the best way for Trump and the Republicans to limit the electoral consequences would be to find an off-ramp to the war "real soon."