Editor's note: Ruth May wrote this column in August 2017. Click here for an extensive update.

Party loyalty is often cited as the reason that GOP leaders have not been more outspoken in their criticism of President Donald Trump and his refusal to condemn Russia's interference in the 2016 presidential election. Yet there may be another reason that top Republicans have not been more vocal in their condemnation. Perhaps it's because they have their own links to the Russian oligarchy that they would prefer go unnoticed.

Donald Trump and the political action committees for Mitch McConnell, Marco Rubio, Scott Walker, Lindsey Graham, John Kasich and John McCain accepted $7.35 million in contributions from a Ukrainian-born oligarch who is the business partner of two of Russian president Vladimir Putin's favorite oligarchs and a Russian government bank.

During the 2015-2016 election season, Ukrainian-born billionaire Leonard "Len" Blavatnik contributed $6.35 million to leading Republican candidates and incumbent senators. Mitch McConnell was the top recipient of Blavatnik's donations, collecting $2.5 million for his GOP Senate Leadership Fund under the names of two of Blavatnik's holding companies, Access Industries and AI Altep Holdings, according to Federal Election Commission documents and OpenSecrets.org.

Marco Rubio's Conservative Solutions PAC and his Florida First Project received $1.5 million through Blavatnik's two holding companies. Other high dollar recipients of funding from Blavatnik were PACS representing Wisconsin Governor Scott Walker at $1.1 million, South Carolina Senator Lindsey Graham at $800,000, Ohio Governor John Kasich at $250,000 and Arizona Senator John McCain at $200,000.

In January, Quartz reported that Blavatnik donated another $1 million to Trump's Inaugural Committee. Ironically, the shared address of Blavatnik's companies is directly across the street from Trump Tower on 5th Avenue in New York.

Len Blavatnik, considered to be one of the richest men in Great Britain, holds dual citizenship in the U.S. and the U.K. He is known for his business savvy and generous philanthropy, but not without controversy.

In 2010, Oxford University drew intense criticism for accepting a donation of 75 million pounds from Blavatnik for a new school of government bearing his name. Faculty, alumni and international human rights activists claimed the university was selling its reputation and prestige to Putin's associates.

Blavatnik's relationships with Russian oligarchs close to Putin, particularly Oleg Deripaska, should be worrisome for Trump and the six GOP leaders who took Blavatnik's money during the 2016 presidential campaign. Lucky for them no one has noticed. Yet.

Oleg Deripaska is the founder and majority owner of RUSAL, the world's second largest aluminum company, based in Russia. Len Blavatnik owns a significant stake in RUSAL and served on its Board until November 10, 2016, two days after Donald Trump was elected.

Deripaska controls RUSAL with a 48 percent majority stake through his holding company, EN+ Group, and the Russian government owns 4.35 percent stake of EN+ Group through its second-largest state owned bank, VTB. VTB was exposed in the Panama papers in 2016for facilitating the flow of billions of dollars to offshore companies linked to Vladimir Putin and is under sanctions by the U.S. government.

Deripaska has been closely connected to the Kremlin since he married into Boris Yeltsin's family in 2001, which literally includes him in the Russian clan known as "The Family."According to the Associated Press, starting in 2006, Deripaska made annual payments of $10 million to Paul Manafort through the Bank of Cyprus to advance Putin's global agenda.

Len Blavatnik's co-owner in RUSAL is his long-time business partner, Viktor Vekselberg, another Russian oligarch with close ties to Putin. Blavatnik and Vekselberg hold their 15.8 percent joint stake in RUSAL in the name of Sual Partners, their offshore company in the Bahamas. Vekselberg also happens to be the largest shareholder in the Bank of Cyprus.

Another oligarch with close ties to Putin, Dmitry Rybolovlev, owns a 3.3 percent stake in the Bank of Cyprus. Rybolovlev is known as "Russia's Fertilizer King" and has been in the spotlight for several months as the purchaser of Trump's 60,000 square-foot mansion in Palm Beach. Rybolovlev bought the estate for $54 million more than Trump paid for the property at the bottom of the crash in the U.S. real estate market.

The convoluted web that links Putin's oligarchs to Trump's political associates and top Republicans is difficult to take in.

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Trump and Putin have a common approach to governance. They rely heavily on long-term relationships and family ties. While there have been tensions between Putin and Deripaska over the years, the Kremlin came to Deripaska's rescue in 2009 when he was on the verge of bankruptcy by providing a $4.5 billion emergency loan through state-owned Vnesheconombank (VEB), where Putin is chair of the advisory board.

VEB, known as President Putin's "pet bank," is now in crisis after sanctions applied by Europe and U.S. in 2014 have isolated it from the international banks that were the sources of its nearly $4 billion in hard currency loans that, according to Bloomberg, mature this year and in 2018.

Russia's international currency reserves are near a 10-year low, which has put further pressure on the president of VEB, Sergey Gorkov, to find sources of international rescue capital. Notably, it was Gorkov who met secretly with Jared Kushner in December at Trump Tower. Kushner's failure to report the meeting with Gorkov has drawn the attention of the Senate intelligence committee that now wants to question Kushner about the meeting.

Ruth May is a business professor at the University of Dallas and an expert on the economies of Russia and Ukraine. She wrote this column for The Dallas Morning News. Twitter: @ruthcmay

CORRECTION, 12:11 p.m., August 7: The headline on an earlier version of this column incorrectly said Blavatnik is Russian. He was born in Urkraine during the Soviet era.

An earlier version of this column used the name Leonid "Len" Blavatnik. He changed his first name to Leonard.

The column has also been updated to remove language describing the online presentation of a press release about Blavatnik resigning from the RUSAL board because it lacked context.

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