New York (CNN Business) Elizabeth Warren doesn't just pose a threat to Wall Street. Her rising 2020 polling numbers are also striking fear in the heart of Big Oil.

Warren, currently the odds-on favorite to be the Democratic presidential nominee, wants to ban fracking "everywhere." And the Massachusetts senator pledged to immediately sign an executive order to stop all new offshore drilling leases. Both steps go further than her main rival, former Vice President Joe Biden.

It would be wildly bullish for crude oil prices. We'd be heading back to triple-digit prices very fast."

Warren's aggressive plan for fighting the climate crisis could have profound consequences for the oil and gas industry. Although an outright fracking ban seems unlikely to get through Congress and the courts, such a move would halt America's historic shale oil boom in its tracks, drive up gasoline prices, threaten good-paying jobs and make the nation more dependent on foreign oil.

"It would vaporize the oil and gas boom in the United States," said Bob McNally, president of Rapidan Energy Group, a consulting firm that advises energy companies and investors. "There is palpable concern in the oil and gas industry."

Wall Street analysts are already warning shareholders about the potential hit to the share prices of oil companies, which remain widely held in portfolios despite the climate crisis.

Pioneer Natural Resources PXD ExxonMobil XOM Chevron CVX "We think the greatest risk to energy companies would occur if Democratic candidate Elizabeth Warren wins," RBC Capital Markets wrote in a report published on Monday. The firm said it would be "very bearish" for a wide range of oil companies, including drillers such as, oilfield service firms and even integrated companies likeand

Warren's campaign declined to comment. But the candidate has defended her aggressive stance by arguing the world doesn't have the luxury of playing it safe.

"Taking bold action to confront the climate crisis is as important — and as urgent — as anything else the next president will face. We cannot wait," Warren wrote in a Medium post last month.

The best-case scenario for the oil industry could be the reelection of President Donald Trump, a climate skeptic who has actively supported the fossil fuel industry by slashing environmental regulations and promoting energy exports.

Democrats have taken a much more skeptical approach towards Big Oil than Trump as they pledge to tackle climate change. The leading candidates have called for ending fossil fuel subsidies

Besides Warren, Democratic presidential nominees Bernie Sanders, Kamala Harris and Cory Booker have also pushed to ban fracking , the controversial drilling technique that involves shooting water, sand and other compounds underground to release trapped oil and gas. Fracking has sparked concerns of contaminated drinking water, methane emissions and even earthquakes.

That's why environmental groups strongly support a fracking ban.

"A clean energy economy built to tackle the climate crisis cannot include fracked gas, which is a bridge to climate disaster," Ariel Hayes, national political director at the Sierra Club, said in a statement to CNN Business.

'Wildly bullish' for oil prices

Fracking, which gained popularity in the early 2000s, has made the United States the world's leading producer of natural gas and, more recently, the top oil producer . In 2016, fracking accounted for more than two-thirds of all oil and natural gas wells drilled in the United States, according to the Energy Information Administration

Driven by the shale revolution, US oil production has more than doubled over the past decade to about 12 million barrels per day. That surge of oil has cushioned the blow from recent events, including oil barrels sidelined by the attack on Saudi Aramco and US sanctions on Iran and Venezuela.

An outright fracking ban would probably send crude oil prices soaring because the United States produces more oil than any other country on the planet. The world is relying on US oil shale oil as the main source of growth for the next several years.

"It would be wildly bullish for crude oil prices. We'd be heading back to triple-digit prices very fast," said McNally, a former energy official under President George W. Bush.

Oil jobs at risk

But it wouldn't be bullish for the oil industry. That's because the fracking ban would probably cause highly leveraged US shale oil producers to go bankrupt, or at least have limited financial firepower to take advantage of high prices.

"They will have been regulated out of business," McNally said. "And the US oil companies that remain will get blamed for high oil prices."

A fracking ban could wipe out countless good-paying jobs in the oil and gas industry.

"You'd have layoffs, everything from the field hands up to the C-Suite," said Jeff Bush, president of oil and gas recruiting firm CSI Recruiting.

A 2017 study paid for by the American Petroleum Institute found that a fracking ban would cause the loss of nearly 6 million jobs and lift household energy spending by $4,500 a year.

Warren has pledged to create new jobs to help workers who are hurt by the transition to a greener economy.

Senator Elizabeth Warren has pledged to immediately put a stop to new fossil fuel leases for drilling offshore and on public lands.

"We will no longer force workers to make the impossible choice between fossil fuel industry jobs with superior wages and benefits and green economy jobs that pay far less," Warren wrote in the Medium post.

A fracking ban might not have a large impact on prices if oil demand weakened because of a rapid shift towards electric vehicles

However, most forecasters expect the world's appetite for oil will rise for many years, if not decades. And even Warren's own energy plan doesn't call for 100% zero emissions for new vehicles until 2030.

That means diminished domestic oil production would likely make America more dependent on foreign crude, undoing its strides toward energy independence.

"It's not going to reduce consumption," said Bush. "It just means we'd be buying more oil from overseas. I don't think anybody wants that."

An outright fracking ban also would require an act of Congress, according to analysts.

Such legislation would be unlikely to get through Congress because Republicans are widely expected to maintain control of the Senate. Even if the Senate flipped, moderate Democrats in oil-producing states such as Colorado and New Mexico would face pressure to oppose such a ban.

"There is no real clean path towards a fracking ban," said Josh Price, senior analyst at Height Capital Markets. "It seems completely unrealistic, close to impossible."

Federal drilling ban could slow oil boom

Still, Warren could take regulatory and executive actions aimed at discouraging fracking.

For instance, RBC said Warren would probably be able to ban fracking and all output on federal lands. Oil output on federal lands is about 2.7 million barrels per day, or 22% of total output.

If such a ban took effect in early 2021, it would slash US oil production by about 300,000 barrels per day that year, RBC said. And by 2025, the firm's US oil production forecast would decline by 1.2 million barrels per day.

The loss of US barrels would drive global oil prices $5 to $10 higher, lifting gasoline prices by 10 cents to 25 cents a gallon, according to RBC. And federal oil and gas revenue would tumble by up to $20 billion.

In sum, even though energy investors might respond negatively to a Warren victory, her proposed crackdown on Big Oil would face enormous challenges, from court fights and economic pressure to a potential political backlash.

"The market could overreact," RBC analysts wrote, "which may provide fundamental buying opportunities."

In other words, Warren's bark may be tougher than her bite, at least when it comes to oil.