President Donald Trump’s nominee for U.S. Interior Secretary and his former lobbying firm have donated almost $1 million to senators who will vote on his confirmation since 2013.

David Bernhardt, a partner at the law and lobbying firm Brownstein Hyatt Farber Schreck, was confirmed as the Interior Department’s deputy secretary in 2017. He has served as the department’s acting secretary since former Interior chief Ryan Zinke resigned in December.

A MapLight review of campaign finance data found that Bernhardt, Brownstein Hyatt employees and the firm’s political action committee contributed more than $225,000 to members of the Senate Energy and Natural Resources Committee between 2013 and 2018. The panel will hold a hearing on his nomination next week.

The firm and its employees also donated more than $960,000 to current members of the Senate, who will cast the final vote on Bernhardt’s confirmation.

Colorado’s senators, Democrat Michael Bennet and Republican Cory Gardner, were the top recipients of cash from Brownstein Hyatt, which has a major lobbying presence in Denver. The third-biggest haul went to Senate Majority Leader Mitch McConnell, R-Ky. Bennet voted to confirm Bernhardt as deputy secretary but has announced he will oppose his nomination to lead the agency.

Throughout his time at the Interior Department, Bernhardt has faced criticism for his past law and lobbying work. He has reportedly sought to limit potential conflicts of interest by carrying around a card listing roughly two dozen former clients, which included oil and gas companies like Halliburton and Noble Energy.

The list, however, didn’t stop Bernhardt from allegedly violating an executive order by Trump requiring that administration officials avoid working on any issues that they had lobbied on within the past two years.