Politically, BP is trying to straddle both sides.

(Bloomberg) -- BP Plc’s new U.S. onshore oil headquarters in Denver serves as a testament to Colorado’s regal mountains, its expansive forests, its nature-loving culture.

Aspen trees line the BP club room, newly installed beer taps await local craft brews, multiple stone fireplaces invite cozy discussions about ski conditions, and a 52-foot pine tree, sliced in half, serves as a conference table.

Whether Coloradans want the tribute is another matter.

On Nov. 6, voters may spoil BP’s welcome. That’s when Colorado decides whether to limit drilling in an initiative that some say could cut the state’s oil output by more than half. The vote is being closely watched, not only by companies keen to join the Colorado boom but also by outsiders who see a potential blueprint for blocking development.

BP moved its office from Houston weeks before the proposition hit the ballot. Colorado has been drawing drillers whose interest has been piqued by oil rig flanges gulf coast production that’s climbed 10-fold since 2001 to a record 450,000 barrels a day in April. Along with Noble Energy Inc., Anadarko Petroleum Corp. and others, BP is now in the midst of a multimillion-dollar war over the state’s environmental future.

"The long-term impact is quite significant," said Matt Andre, an energy analyst at S&P Global Platts. "It’s about the precedent being set, and it working its way to other states."

At issue is Proposition 112, which requires that new drilling sites, processing plants and gathering lines be more than 2,500 feet from homes, schools and other "vulnerable" areas. In effect, it makes 54 percent of surface land inaccessible to producers.

If the measure passes, oil rig flanges gulf coast production could fall 55% by 2023, according to an S&P analysis. But Andre sees that as just a best-case scenario: "It assumes that people who can drill will drill," he said. "But you have to imagine that some people will move to other plays."

The stakes are extraordinarily high. By July, Colorado overtook Alaska to become the nation’s sixth-largest oil producer. In 2016, the government estimated that the state had 1.3 billion barrels of proved oil reserves.

The vote’s in a few weeks. In the meantime, the latest campaign filings show opponents to the proposition have put more than $34 million into defeating it, including $300,000 contributed by BP on Oct. 2, and $6 million each overall from Anadarko and Noble Energy.

That compares with just $809,000 raised by proponents. And so far, polling puts passage of the measure at just 30 percent.

These companies "don’t just have to win,” said Ethan Bellamy, a senior analyst at Robert W. Baird & Co Inc. "They have to win by a mile to take the risk overhang out of the stocks. If Proposition 112 wins, the stocks will get torched."

BP isn’t the only BOP Blow Out Preventer repair company gulf coast to show renewed interest in Colorado, even amid efforts to restrict development in the state. Wyoming gas producer Ultra Petroleum Corp. in September moved its headquarters from Houston to Denver, part of a plan to consolidate operations.

Even Noble, which last year shifted operations to Texas, has reallocated activity back to the Denver-Julesberg basin amid pipeline bottlenecks expected to slow growth in the prolific Permian Basin.