Sen. Bernie Sanders, the populist who challenged Hillary Clinton from the left in the presidential primary, laced into President-elect Trump Tuesday for failing to live up to his promise to "drain the swamp" in Washington by breaking his promise to keep lobbyists out of the GOP-run White House.

Sanders, I-Vt., teamed up with Sen. Sheldon Whitehouse, D-R.I., Tuesday to rail against Trump's decision to allow lobbyists and wealthy corporate interests on his transition team. The pair also took Trump to task for his remarks during a CBS News "60 Minutes" interview in which he appeared to reverse himself on his pledge to deny lobbyists jobs in his administration.

"Sen. Whitehouse and I are deeply concerned about what the president-elect has said on lobbyists, Wall Street and prescription drugs is not going to be implemented," Sanders told reporters on a conference call Tuesday.

"It's dismaying that his very opening act while president-elect is to violate the basic principles and the basic statements of his own campaign," Whitehouse said. "And if he's willing to do that at this juncture, then it would appear to me that he would be willing to violate all the others as well."

The White House that is taking shape so far, Whitehouse said, is hardly the populist-oriented administration Trump promised. "We're basically back to the Koch brothers infiltration of a Koch presidency, and they will be calling the shots."

Lobbyists and special interests have been a frequent target of Trump since his campaign's early days. He has complained that lobbyists and special interests basically own the political class in Washington and corporate greed has destroyed U.S. manufacturing jobs in the rust belt states that he won handily.

But in the days since his unexpected victory, Trump has put some of the country's wealthiest industries and lobbyists in charge of hiring and planning. Rebekah Mercer, a daughter of billionaire Robert Mercer, is an influential voice behind the scenes, serving on a 16-person executive committee overseeing the transition, along with Steven Mnuchin, New York financier Anthony Scaramucci and Silicon Valley investor Peter Thiel.

Meanwhile, Washington lobbyists are also playing key roles, including Steven Hart, chairman of the law and lobbying shop Williams & Jensen, and Michael McKenna, an energy company lobbyist.

Rudy Giuliani, who is reportedly contending to become Trump's secretary of state, on Tuesday came under scrutiny for his firm's decision to accept large consulting fees from a number of U.S. foes, including an exiled Iranian political party and Venezuela's Citgo. His consulting firm, Giuliani Partners, also advised Qatar's state-run oil company on security at a natural gas plant, the Wall Street Journal reported. Qatar is a U.S. ally and home to a large contingent of U.S. troops, but it also is accused of trying to prevent a U.S. attempt to arrest Khalid Sheikh Mohammed before he went on to mastermind the 9/11 attacks.

In mid-October, Trump released a five-point plan for ethics reform in Washington, accompanied with his promise to "drain the swamp."

The plan, however, did not promise a lobbyist-free Trump administration. Instead, in its first point, Trump pledged to re-institute a ban on all executive branch officials lobbying the government for five years after they leave government service, a rule he said he would ask Congress to pass into law so that it cannot be lifted by executive order.

He also promised to place a five-year ban on lobbying by former members of Congress and their staffs and to expand the definition of lobbying to close "all loopholes" that former government officials use by labeling themselves consultants and advisers when everyone knows they are lobbyists.

Fourth, he said he would issue a lifetime ban against senior executive branch officials lobbying on behalf of a foreign government. Fifth, he said he would ask Congress to pass a campaign-finance reform package that prevents registered foreign lobbyists from raising money in American elections.

"This will go a long way in ending government corruption," Trump said in a statement accompanying the release of the plan.