Sticker shock awaits you the next time you pull up to the pump to fill up as steadily rising gasoline prices are nearing their highest level since 2014.

The price surge comes just ahead of the November midterm elections when California will vote on rolling back its gas tax, USA Today explains.

Average prices topped $2.91 a gallon for unleaded Thursday for the first time since June, having risen 7 cents a gallon in the past month, AAA reports. 

The average gas price is the most expensive for the start of October since 2014, AAA said. Prices are now four cents higher than a month ago and 32 cents higher than a year earlier.If they rise by about another seven cents, they will be the highest in four years, USA Today reports.

The three states around the country with the cheapest gas are Mississippi ($2.57), Alabama ($2.57) and South Carolina ($2.58), while Florida and Michigan have witnessed the biggest increase in gas prices, with a 10 cent hike in both states, AAA said.

Gasoline prices are moving higher because the cost of oil has risen amid stronger global economies and international politics.

"It's been about demand growth worldwide," said Tom Kloza, global head of energy analysis for the Oil Price Information Service.  And when it comes to sanctions on Iran, a major oil producer, "there's no shortage of scary comments" that inject fear into the market and drive up prices further, Kloza told USA Today.

To be sure, rising gas prices could put a dent in consumers' budgets, leading to cutbacks in other areas of spending. Prices may be rising because of concerns about demand, as well as higher prices this summer for crude oil, AAA explained to CBS MarketWatch.

"The last quarter of the year has kicked off with gas prices that feel more like summer than fall," said Jeanette Casselano, AAA spokesperson, in a statement. "This time of year, motorists are accustomed to seeing prices drop steadily, but due to continued global supply and demand concerns, as well as very expensive summertime crude oil prices, motorists are not seeing relief at the pump."

In California, voters will soon decide whether to drive out a gasoline tax increase passed to fund transportation projects across the state, the Associated Press reported.

Proposition 6 seeks to repeal last year's decision by the Democratic-led Legislature to raise fuel taxes and vehicle fees to pay for roughly $5 billion a year in highway and road improvements and transit programs.

Republicans and Democrats agree the sprawling state known for its car culture needs a transportation overhaul, with suburban commuters clamoring for better freeways and urban dwellers demanding mass transit.

But how to fund these fixes has been hotly disputed, prompting the recall of a Democratic state lawmaker who voted for the tax increase and spurring Republican candidates in races for federal, state and local offices to take up the call for repeal.

"Republicans hate increases in taxes," said Fred Smoller, a political science professor at Chapman University in Orange County, where Republicans face several competitive congressional races. "They also need something on the ballot to, as they say, 'gin the base' for the fall."

Gov. Jerry Brown signed the transportation deal last year to raise $52 billion over a decade for road and bridge repairs. Nearly half the money will come from fuel taxes, with a 12 cent-per-gallon boost in gasoline excise taxes that took effect last November.

The repeal initiative — a constitutional amendment proposed by San Diego talk radio host and Republican former councilman Carl DeMaio —is backed by Republican gubernatorial candidate John Cox and taxpayer advocates. It is opposed by construction industry and firefighter unions.

Supporters raised about $5 million through September, according to campaign finance reports. That's a far cry from the $30 million raised to oppose the initiative, which would also require voter approval to raise vehicle or fuel taxes in the future.