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Scott Mason is joining the top government affairs firm Holland & Knight later this month

Mason will take on a role as senior policy adviser in the firm's public policy and regulatory practice division

Washington CNN  — 

One of President-elect Donald Trump’s top congressional liaisons is making the jump to K Street instead of joining the Trump administration.

Scott Mason, who worked as the Trump campaign’s director of congressional relations for the House of Representatives, is joining the top government affairs firm Holland & Knight later this month, a source familiar with the move told CNN on Tuesday. A spokeswoman for Holland & Knight confirmed the hire.

Mason will take on a role as senior policy adviser in the firm’s public policy and regulatory practice division, where he will help the firm navigate the waters of dealing with the Trump administration. He is likely to eventually register as a lobbyist to push the agenda of the firm’s clients in Washington, the source familiar with the move said.

He had been offered a post in the Trump administration as a senior White House adviser at the Department of Interior, a new position the Trump administration is planning on adding within executive departments to better coordinate with the White House on its policy and political agenda, the source said.

The hire comes as Trump prepares to take office and where he will be tested to implement his rhetorical promise to “drain the swamp,” a pledge he made to voters that he would work to rid Washington of special interests.

As part of that plan, Trump has promised to institute a ban barring administration officials from working as lobbyists for five years after leaving the White House.

But that decision is also making some wary of joining the administration, and the source familiar with Mason’s hire said the five-year ban was a factor in his decision not to join the administration.

Mason, a North Carolina native, previously headed up the government affairs division at Lowe’s for 10 years before joining the Trump campaign, where he became one of the campaign’s first Washington-based staffers.

Sen. Richard Burr, R-North Carolina, and Rep. Chris Collins, R-New York, both lent their voices to praise Mason in a press release the lobbying giant Holland & Knight plans to publicly release later Tuesday.

Burr noted that he’s worked with Mason since his first term in Congress and cited his relationships on Capitol Hill and with the incoming administration as a “huge asset for him.”

Collins, who led the pro-Trump caucus on Capitol Hill, credited Mason with helping build support for Trump on Capitol Hill. Mason helped grow the Trump caucus from a group of a handful of congressmen to more than half the Republican caucus by Election Day.

“Scott played a key role in helping us build a strong and effective Trump Caucus in the House of Representatives,” Collins said. “I know members of the Trump Caucus appreciate his efforts, value his friendship and look forward to continue working with him.”

Mason also helped run a Congressional surrogacy program, getting members of Congress to join Trump at rallies in key districts.

Mason is not the first member of Trump’s team to head for the lobbying world.

Corey Lewandowski, Trump’s former campaign manager, started his own lobbying and public affairs firm last month with another former Trump aide, Barry Bennett.