The pharmaceutical industry doesn’t just contribute to patient groups or the lawmakers themselves through campaign contributions to assert influence. It floods the U.S. Capitol with lobbyists.

A Tarbell analysis of lobbying disclosures found that the leading drugmakers that make up the Pharmaceutical Research and Manufacturers Association, and the association itself, have spent $1.8 billion lobbying the federal government since 1999. The pharmaceutical and health products industries as a whole spent $3.7 billion during the same timeframe, according to the Open Secrets database maintained by the Center for Responsive Politics.

This money pays for a fleet of lobbyists who regularly drop in on lawmakers, their staffers and regulators to push legislation favorable to their clients and to quash bills their clients consider problematic.

This list of PhRMA members includes household names like Pfizer, Merck, AstraZeneca, and Johnson & Johnson.

PhRMA itself spent an average of $17 million on lobbying per year during that period, totaling more than $320 million since 1999, the Tarbell analysis revealed. This is more than all but a handful of companies and groups, according to the Open Secrets database.

And it is not just the money the industry spends that gives it an outsized influence in the legislative and regulatory process, it’s also the people doing the lobbying.

Dr. Sammy Almashat, a physician and research associate for the watchdog group, Public Citizen, described the “revolving door” from Capitol Hill to K Street: “It is well recognized within the lobbying industry that one of the most effective methods of swaying a government official is by sending in former colleagues to make the client’s case,” Almashat wrote. “The pharmaceutical industry is a bastion for well-connected former policymakers who have gone through the revolving door after a stint in government.”

This year, PhRMA has a team of 164 lobbyists, nearly 72 percent of whom were once government employees, according to Open Secrets data.

Three lobbyists on PhRMA’s payroll once served in the highest rungs of the federal government: Bill Paxon and Ron Klink were members of the U.S. House and Jon Kyl was a member of the Senate.

Of the three, Kyl — a once powerful senator from Arizona — is the most recent lawmaker to go through the revolving door.

As Senate Minority Whip, Kyl was one of Washington’s most influential lawmakers. Considered a staunch conservative, Kyl, whose career in Congress spanned three decades, also sat on the Senate’s Finance Subcommittee on Health Care, which makes tax and financing decisions that affect health care stakeholders.

After leaving the Senate in 2013, Kyl quickly found a new job at Covington & Burling, a prominent D.C. firm where he lists “health care” as one of his specialties.

An excited Kyl said in a 2013 statement, “I look forward to working with corporate clients to find solutions that will help their businesses grow.”

When he joined Covington & Burling, the firm was already a favorite among the pharmaceutical industry, and one of PhRMA’s go-to shops.

Since 1998, pharmaceutical companies have paid Covington & Burling roughly $19 million to lobby on their behalf, making the industry Covington & Burling’s second-largest customer, according to a Tarbellanalysis of data from the Center for Responsive Politics.

Pharmaceutical companies have paid the firm more than oil and gas, finance and insurance companies combined.

And since Kyl arrived, the pharmaceutical industry has accounted for a greater share of Covington & Burling’s lobbying, Tarbell’s analysis shows. In the past three years, PhRMA itself has paid Covington & Burling nearly $3 million — more than it has paid any other lobby shop.

Similarly, Paxon, a Republican from Buffalo who helped orchestrate the GOP’s takeover of the House in the early ’90s, left Congress and joined a powerful lobbying firm. Once considered a rising star in his party, Paxon later took his apparent knack for campaigning and deal making to one of D.C.’s top firms, Akin Gump Strauss Hauer & Feld.

For at least the past 15 years, Akin Gump has been one of the highest-earning lobbying firms in the country, according to the Center for Responsive Politics. Historically, only one other industry has paid Akin Gump more than the pharmaceutical industry, a Tarbell analysis shows.

Since 1998, the firm has pulled in more than $37 million lobbying for pharmaceutical companies. Nearly $6 million of which came from PhRMA.

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This year, PhRMA has paid Akin Gump $240,000, more than all but two firms on its payroll.

Speaking to the Houston Chronicle in 2013, Klink, a Democrat from Pennsylvania, spoke about the close ties he developed over his eight years in Congress. Lobbyists and lawmakers, he said, aren’t that different.

“We’re all kind of doing the same thing,” Klink said then. “The fact that I don’t have to show up for votes and get to keep the money now is a benefit.”

In Congress, Klink sat on the influential Energy and Commerce Committee — experience that Klink, on his LinkedIn page, says has made him a better lobbyist.

As a lobbyist, Klink has “used my expertise from my years on the Energy and Commerce Committee to provide opportunities and solve problems for our clients.”

Klink’s firm, Nelson Mullins Riley & Scarborough, is a smaller operation than Covington & Burling or Akin Gump, but has still pulled in more than $2 million from pharmaceutical companies since 2004. About a third of this has come from PhRMA.

This year, PhRMA has paid Klink’s firm, Nelson Mullins Riley & Scarborough, $90,000.

Yet it’s not just high profile lawmakers defecting to the influence industry. The vast majority of former government employees now working at lobby shops were never senators or representatives, but congressional and agency staffers.

Of PhRMA’s 118 ex-government employees, for example, 115 were not former congressmen, and many were “legislative assistants” or “legislative directors,” jobs that rarely pay more than $100,000. These staffers are worth far more than that to the biggest lobbying firms and their clients.

It’s this money and influence that allows the pharmaceutical industry to have an outsized influence on policy decisions, said Daniel Auble, who tracks lobbying activity at the Center for Responsive Politics.

“Congress does not hear as often from the little guy,” he said. “But they do hear from lobbyists on a daily basis.”

This lobbying power was brought to bear in 2016 for one of the final major pieces of legislation that Barack Obama signed into law: The 21st Century Cares Act.

When Obama signed it into law in December 2016, it was one of the year’s most expensive and most lobbied pieces of legislation, according to the Center for Responsive Politics. More than 1,500 lobbyists worked on the bill.

The Cures Act won broad support by promising increased funding to the National Institutes of Health, but buried in the bill’s 900-some pages are provisions that critics say will “gut” the Food and Drug Administration, loosening the agency’s regulatory authority and lowering the standards that drugs and medical devices must meet before they can enter the market.

The act barreled through the 114th Congress and passed with few dissenting votes cast. In the Senate, Bernie Sanders (I-VT) and Elizabeth Warren accounted for two of the five nays. The others were Jeff Merkley (D-Ore), Ron Wyden (D-Ore.) and Mike Lee (R-Utah).

Some doctors denounced the Cures Act, including one oncologist who told the Health News Review that “10 years from now someone with a cancer diagnosis will be worse off with this bill…People will be exposed to more things that don’t work,” he said, because the studies will be inadequate before products go to market.

But the millions spent on lobbying spoke far louder than the bill’s band of detractors. And the roughly 1,600 lobbyists working on behalf of nearly 460 groups far outnumbered them.

The 21st Century Cures Act is emblematic of the way laws get passed in Washington today: money is power, and no sector has more of both than the pharmaceutical industry.

Put simply, Auble said, “Pharmaceuticals is by far the industry spending the most on influencing policy in Washington.”