(Bloomberg) -- An international energy adviser to President Donald Trump, who was sought by congressional Democrats as part of their impeachment inquiry, is leaving the White House, according to three people familiar with the matter.

Wells Griffith, who has been serving as a senior director for international energy and environment on the National Security Council, is set to join the Overseas Private Investment Corp. next week, said two of the people. All three asked not to be named discussing a personnel issue.

The move is part of a broader effort to streamline the National Security Council, with more matters shifted to the National Economic Council, according to two of the people. National Security Adviser Robert O’Brien previously outlined his ambitions to pare NSC staff in an October Washington Post opinion piece.

Griffith, a former Energy Department official who also worked on Trump’s 2016 campaign, has dealt with an array of international energy matters in his White House role, including sanctions on Iran and Venezuela. Griffith last year also served as the face of the Trump administration at international climate negotiations in Poland, where he was part of a panel touting technology to produce cleaner coal-fired power.

Griffith helped broker a deal to export U.S. coal to Ukraine during his tenure at the Energy Department under Trump.

Griffith could have a similar portfolio at OPIC, a U.S. government agency that helps finance projects in developing countries. The Trump administration has tried to encourage multilateral development banks and other international lenders to support coal-fired power plants and natural gas.

“He played a really big role in defining the president’s foreign energy policy; he’s now in an excellent position to implement it,” said George David Banks, a former international energy adviser to Trump.

Griffith last month rebuffed a subpoena from House Democrats to be deposed as part of the inquiry into Trump’s dealings with Ukraine, citing White House counsel guidance against participating.

--With assistance from Jennifer Jacobs.

To contact the reporters on this story: Jennifer A. Dlouhy in Washington at jdlouhy1@bloomberg.net;Ari Natter in Washington at anatter5@bloomberg.net

To contact the editors responsible for this story: Jon Morgan at jmorgan97@bloomberg.net, John Harney

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