Bargain-basement natural gas prices are sending New England's electricity bills through the roof – and House Republicans warn it's an omen of worse to come nationwide.

Last week, barely half a year after the polar vortex sent frigid weather swirling across much of the country, utility National Grid announced that rates in New England would leap by 37 percent, ratcheting up a household’s average bill by about $33 a month over last year.

The reason: gas prices are way down, and as a result, demand is way up – but the region’s two major natural gas pipelines are already practically filled to the brim, constricting supply and sending already-elevated rates ever higher.

“We’re a stranded region,” says Gilbert Metcalf, an economics professor at Tufts University. “We have a major bottleneck for getting natural gas into New England.”

House Republicans say federal overreach is to blame for the supply constraints, their chief culprit a favorite target: the Environmental Protection Agency.

Since June, the committee has warned that the EPA's proposed Clean Power Plan, which would limit carbon dioxide emissions from existing power plants, would sharply raise prices across the country, either by compelling plants to install costly new technology or forcing them to shut down altogether. Last week, it pointed to New England as proof.

"More utilities are switching from coal to natural gas as EPA regulations force coal-fired power plants to retire prematurely," the majority members of the Energy and Commerce Committee declared in an email blast and blog post shortly after the National Grid announcement.

Regulatory "red tape," it added, has also slowed the federal approval process for new pipelines, sowing risk and uncertainty and discouraging companies from building a new pipeline.

"You have a set of rules there in place that make it very difficult to take expensive projects, big projects, that take a long time from concept to completion," says Rep. Mike Pompeo, R-Kan., who introduced a bill last year aimed at speeding-up pipeline approvals. "What you can’t do is just sit on the application. And that’s what we’re finding government doing so often. They won’t say yes, but they refuse to say no."

But industry insiders, not to mention consultants and academic scholars, offer a sharply different view from the policymakers on Capitol Hill.

“It’s a complete non-sequitur,” Metcalf says. “It’s absolutely unrelated to what the EPA is doing.”

New England suffers a unique set of circumstances leading to the its rate increases. Already, aging coal and nuclear power plants in the region are being shut down, replaced with natural gas plants that are cheaper and easier to build. What's more, during the past decade, hydraulic fracturing, or fracking, has flooded the market with cheap natural gas, offering further incentive for power companies to change fuels.

As a result, the Northeast has become heavily reliant on natural gas for its electricity – more so than other areas of the U.S. And like any portfolio that lacks diversification, it leaves investors – or in this case, ratepayers – exposed.

“In the non-winter months, it’s a very inexpensive way to run our electricity market, and because of those market forces, we’ve always had lots of natural gas in Massachusetts,” says Erin Baker, an industrial engineering professor at the University of Massachusetts who specializes in environmental economics. “But in the winter, when there’s demand for heating as well as electricity, the problem is the pipelines.”

That's because natural gas isn’t just used to generate electricity, it’s harnessed to heat homes, too. And the two sectors, heat and power, buy natural gas in fundamentally different ways.

Heat suppliers – as well as factories and other industrial companies – get their gas under long-term contracts, locking in low rates for years at a time, experts say. They also buy plenty of it: Come winter, much of the gas that flows through the region’s two pipelines is used for heating. The scant amount that's left over goes to the electric generating companies, which bid against one another for the fuel.

"If there are 100 units of gas [in a pipeline], and on any given day they need 95 of those to serve the gas [heating] market, there’s only 5 units left to serve the highest bidder," says Peter Abt, managing director of oil and gas planning at Black and Veatch, an engineering, construction and industry consulting firm.

And ahead of what experts fear could be another unusually cold winter, those auction prices have shot skyward – prices that the generating companies can then pass down the line, to the wholesalers, the distributors, and the local utilities, until they finally reach consumers. Which means that for the companies that actually do the bidding in the first place, there's little reason to stake money on a major new pipeline if they're not on the hook in the first place.

"There's not an incentive to purchase [pipeline] capacity," says Greg Crisp, a general manager at Spectra Energy, which owns one of the two major pipelines serving New England.

There are other disincentives, too. Companies that buy the electricity that power companies generate will, of course, prefer the lowest price. That should keep costs low, but it also means that if a company takes the risk of investing in a new pipeline, it might not be able to include that cost in the price of its gas – it could be too expensive.

"They’d fall to the bottom of the queue," says Kimberly Watson, a president at Kinder Morgan Energy Partners, which owns the other of New England's two pipelines. "There’s not a guaranteed payback."

So in fact, experts say, it isn't federal regulators to blame, it's the market. Demand for the lowest possible electricity prices has discouraged the construction of a new pipeline – and yet, that very project could help satisfy the soaring demand that's been spurred by historically low gas prices.