The midterms might be won or lost on a single issue: The gas tank

The recent surge in gas prices has experts saying the issue could drive the results of November's midterm elections — signaling trouble for Republicans as President Donald Trump admits relief won't likely come before then .

The average national cost of a gallon of regular unleaded topped $4.31 Monday, up 36 percent from more than $3.17 a year ago, according to AAA .

Diesel — which powers delivery trucks, affecting the cost of groceries and other consumer goods — hit a new record high of $6.23 a gallon, up nearly 69 percent.

The situation leaves GOP lawmakers facing a rocky road as they map out their path to victory against Democrats eager to seize control of the House and Senate .

“Gas prices were higher, but then they dropped down and now they’re going back up,” East Carolina University political science professor Brad Lockerbie told TV station WITN last week. “I think what is going to be of concern for the voters is the direction of change right now.”

Rich Meagher, a political science professor at Randolph-Macon College, also said: “This was always going to be, in some ways, the year of affordability.”

He told TV station WRIC: “Donald Trump’s war in Iran is something that has contributed to the instability of gas prices, and I think that Democrats should be really trying to make that connection.”

The latest spike in gas prices helped push the consumer price index up 3.4 percent last month compared to a year ago, the same rate recorded in July — but up 0.4 percent on a monthly basis, according to figures released Friday by the Labor Department.

And although many economic experts have long considered higher gas prices a brief, one-time inflationary shock, Kathy Bostjancic, chief economist at Nationwide, said Trump's ongoing war against Iran means “this is not one and done.”

“It’s unclear when tensions in the Middle East are going to settle down,” Bostjancic told The Associated Press . “This seems like it could be a prolonged disruption.”

A July poll by Politico found that Americans were so upset by gas prices that three in five overestimated the increases at local pumps, with a plurality of 46 percent saying they expected the issue would affect their votes in November.

Nearly 40 percent said they were considering crossing party lines, including 49 percent of self-identified MAGA Republicans and 57 percent of non-MAGA Republicans, according to Politico .

The latest YouGov poll for The Economist magazine, conducted September 4-8, also found that 98 percent of respondents said gas prices had increased over the past year, with 73 percent saying they'd “gone up a lot.”

Trump — who's repeatedly urged voters to “pretend” he's on their November ballots — scored a dismal disapproval rating of 61 percent among those surveyed, compared to 37 percent who approved of his job performance.

Republican Senator Jim Justice of West Virginia, who isn't up for reelection, told MS Now last month that “if you’re not concerned and sympathetic about gas prices for people, then really and truly, we’re not thinking very right, because we got a lot of people that are really hurting.”

Justice, who isn't up for reelection, also said any Republican candidates who weren't worried about gas prices were “living in a cave.”

“The political blowback will be substantial,” he warned.

An unidentified House Republican who represents a swing district also expressed frustration over rising gas prices, telling MS Now: “I wish the administration had a plan.”

“Obviously, the fuel prices are having a devastating impact on people across the district and across the country,” the lawmaker added.

Last week, when salvos between the U.S. and Iran pushed the price of a barrel of Brent crude over $100 for the first time since July, Trump said oil costs would likely remain high through the midterms , the AP reported.

“Right after the election, oil prices are going to be tumbling downward,” said Trump, who's repeatedly predicted a coming end to the war that's now in its seventh month. “I think it’s going to take a little bit longer than the midterm.”

On Monday, Brown University's online Iran War Energy Cost Tracker estimated that the total added costs paid by American consumers was around $106 billion, or about $809 per household, since the Trump launched the war without congressional approval February 28.

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