MONACA, Pa. — President Donald Trump sought to take credit Tuesday for the construction of a major manufacturing facility in western Pennsylvania as he tries to reinvigorate supporters in the Rust Belt towns who helped send him to the White House in 2016.

Trump visited Shell Oil Co.'s soon-to-be completed Pennsylvania Petrochemicals Complex, which will turn the area’s vast natural gas deposits into plastics. The facility, which critics claim will become the largest air polluter in western Pennsylvania, is being built in an area hungry for investment.

Speaking to a crowd of thousands of workers dressed in fluorescent orange-and-yellow vests, Trump said, “This would have never happened without me and us.”

In fact, Shell announced its plans to build the complex in 2012, when President Barack Obama was in office.

A Shell spokesperson said employees were paid for their time attending Trump’s remarks.

Trump used the official White House event as an opportunity to assail his Democratic rivals, saying, “I don’t think they give a damn about Western Pennsylvania, do you?”

The focus is part of a continued push by the Trump administration to increase the economy’s dependence on fossil fuels in defiance of increasingly urgent warnings about climate change. And it’s an embrace of plastic at a time when much of the world is sounding alarms over its impact.

“We don’t need it from the Middle East anymore,” Trump said of oil and natural gas, calling the employees “the backbone of this country.”

Trump's appeals to blue-collar workers helped him win Beaver County, where the plant is located, by more than 18 percentage points in 2016, only to have voters turn to Democrats in 2018's midterm elections. In one of a series of defeats that led to Republicans' loss of the House, voters sent Democrat Conor Lamb to Congress after the prosperity promised by Trump's tax cuts failed to materialize.

Beaver County is still struggling to recover from the shuttering of steel plants in the 1980s that surged the unemployment rate to nearly 30%. Former mill towns like Aliquippa have seen their populations shrink, while nearby Pittsburgh has lured major tech companies like Google and Uber, fueling an economic renaissance in a city that reliably votes Democratic.

Trump claimed that his steel and aluminum tariffs have saved those industries and that they are now “thriving.” a description that exaggerates the recovery of the steel industry.

Trump also took credit for the addition of 600,000 U.S. manufacturing jobs. Labor Department figures show that roughly 500,000 factory jobs have been added under his presidency.

The manufacturing sector has started to struggle this year as the administration intensified its trade war with China, and factory production has declined. Pennsylvania has lost 5,600 manufacturing jobs this year, according to the Labor Department.

The region’s natural gas deposits were seen for a time as a new road to prosperity, with drilling in the Marcellus Shale region transforming Pennsylvania into the nation’s No. 2 state for natural gas. But drops in the price of oil and gas caused the jobs boom from fracking to fizzle, leading companies like Shell to turn to plastics and so-called cracker plants — named after the process in which molecules are broken down at high heat, turning fracked ethane gas into one of the precursors of plastic.

The company was given massive tax breaks to build the complex along with a $10 million site development grant, with local politicians eager to accommodate a multibillion-dollar construction project.

“Fracking for plastic” has drawn criticism from environmentalists and other activists, who warn of potential health and safety risks to nearby residents and bemoan the production of ever more plastic. The sheer quantity of plastic on the planet has overwhelmed landfills, inundated bodies of water, and permeated the deepest reaches of the ocean. Microplastics have also been found in the bodies of birds, fish, whales, and people, with any health impacts largely unknown.

"Of all the things we could invest in, of all the things we should be prioritizing, of all the companies we should be giving our taxpayer money to, this seems like the worst of all worlds," said David Masur, executive director of PennEnvironment, a statewide environmental advocacy organization, who called the project "a pretty big taxpayer boondoggle for a pretty dirty project."

Trump defended the investment in plastics, claiming pollution in the ocean is "not our plastic."

"It's plastics that's floating over in the ocean and the various oceans from other places," he told reporters before boarding Air Force One.

A spokesperson for Shell, Ray Fisher, said the company has “dedicated a great deal of time and resources” to ensure emissions from the plant meet or exceed local, state and federal requirements.

The project has 5,000 construction workers. Once operational, the site will employ 600 permanent employees.

The area still faces headwinds. The nearby Beaver Valley Power Station, a nuclear plant that has employed 850 people, has announced plans to close in 2021. And the Bruce Mansfield Power Plant, once the state’s largest coal-powered plant, announced Friday that it would close this fall, 19 months earlier than expected, at a cost of at least 200 jobs.