One of Hillary Clinton’s staunchest corporate allies in New York is Corning Inc., a glass and ceramics manufacturer that has been listed as a top “Corporate Tax Avoider” because of its failure to pay income taxes on its billions of dollars in profits.

Clinton and the company have an “I’ll scratch your back if you scratch mine” relationship, her State Department emails suggest. One little-noticed email released at the end of February shows that Clinton was personally involved in helping Corning in a trade secrets dispute with China.

Other emails show she and her State Department aides were in frequent contact about various issues with Corning’s CEO and the company’s top government liaison.

The revelation of Clinton’s cronyism is no surprise. The company has been a major Clinton benefactor since her time in the U.S. Senate. Corning executives and employees have poured hundreds of thousands of dollars into her campaign war chests.

Headquartered in a town by the same name, Corning has also donated at least $100,000 to Clinton’s family charity, the Clinton Foundation. And in 2014, the company paid Clinton $225,000 for a corporate speech.

In 2009, shortly after Clinton took over as secretary of state, the company contributed $500,000 to the USA Pavilion at the 2010 Shanghai Expo. Clinton spearheaded an effort to attract corporate donors to the pavilion, which was seen as something of a vanity project for her.

In an April 2014 article about Clinton’s cozy relationship with Boeing, another USA Pavilion donor, The Washington Post reported that the airplane manufacturer’s $2 million donation to the Shanghai project “was helpful to Clinton at a critical moment as she made it her priority to woo support from corporations to revive the American presence at the event.”

“She was widely credited with orchestrating a turnaround, and the can-do image she cultivated as secretary of state has contributed to her status as a Democratic front-runner ahead of the 2016 presidential campaign,” reads The Post article.

Clinton brought a team of campaign fundraisers to help with the effort. One of those was Kris Balderston, a longtime aide to both of the Clintons.

At the Clinton State Department he held the title of special representative for global partnerships. Emails show that he frequently updated Clinton on meetings he held with companies regarding funding of the USA Pavilion.

Balderston joined Clinton last Friday at a round-table event held in Syracuse where the Democratic presidential candidate praised Corning.

“Let’s give Corning a round of applause,” Clinton said.

“Corning is such a great American company and I’m so proud that I’ve been able to partner with you over these years, and I look forward to supporting the work you do going forward,” she added.

A Corning senior vice president, Christy Pambianchi, also took part in the round-table session.

Corning’s corporate strategies are hardly in line with what Clinton’s increasingly progressive party base might consider to be the actions of a “great American company.”

From 2008 to 2012, the company paid nothing in federal income taxes, making it one of the top-10 “Corporate Tax Avoiders” placed on a list that circulated among progressives.

Vermont Sen. Bernie Sanders, Clinton’s primary challenger, also shared the list on his Senate website.

Not only did Corning avoid taxes during that four year stint, the company also received a $10 million tax refund from the IRS. That despite making more than $3.4 billion in profits.

The company also stashed $11.9 billion in offshore tax shelters to avoid paying federal taxes. Clinton has criticized the use of offshore schemes.

Clinton personally intervened to help the company during that same time span, her emails show.

One Jan. 27, 2012 email shows that Clinton was directly involved in a trade secrets dispute involving Corning and the Chinese government.

“I called your office today to give you the heads up on a call that our CEO is going to have with Valerie Jarrett on Monday,” Timothy Regan, Corning’s senior vice president of government affairs, wrote to Clinton’s top foreign policy adviser Jake Sullivan in the email.

“It concerns the Corning trade secret issue in which the Secretary has an interest. She called me on Monday for an update,” Regan wrote.

Clinton also appeared to personally intervene in Jan. 2011 on behalf of Corning.

Robert Hormats, who then served as under secretary of state for economic growth, energy, and the environment, sent a now-redacted email with the subject line “Corning” to Sullivan on Jan. 17, 2011.

[dcquiz] “Can we prepare a non-paper outlining the problem for me to reference and deliver if necessary?” Clinton responded to Sullivan. “Could even include other issues still outstanding.”

On April 19, 2010, Clinton sent Balderston a now-redacted email referring to Corning. Balderston responded thanking her for talking to the company’s CEO, Wendell Weeks.

Clinton asked about Corning again several days later.

“Also, where are we w Corning?” she asked Balderston in an April 25, 2010 email. “Can you consult w EAP and E to find out what we can do?”

“EAP” is an apparent reference to the State Department’s Bureau of East Asian and Pacific Affairs. “E” likely refers to Hormats’ sub-agency.

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