WASHINGTON ― The director of the U.S. Census Bureau is resigning, the Commerce Department announced Tuesday, leaving the government’s lead statistical agency without a clear leader as the bureau ramps up for the massive decennial task of counting the entire U.S. population in 2020.

Census Bureau Director John Thompson’s announcement that he is leaving at the end of June comes less than a week after he testified on Capitol Hill, telling House appropriators that his agency would be able to carry out the Census effectively, despite a number of cost overruns and a lower budget than normal for this point in the 10-year planning cycle.

Normally as Census planning shifts from the seventh year of the decade to the eighth, the budget jumps dramatically. But Congress did not pass the Obama administration’s budget for 2017, leaving the bureau about $160 million short of its $1.61 billion request. The Trump administration’s request for 2018 is essentially flatlined, at a time when the government is usually adding hundreds of millions of dollars to carry out one of the most challenging statistical counts in the world.

On May 3, Thompson told Rep. John Culberson (R-Texas), the appropriations subcommittee chairman overseeing the Census budget, that the bureau would be able to meet the challenges of carrying out the Census in new and cheaper ways.

“We’re glad we’re a priority,” Thompson said of Trump’s budget proposal. “We’re very, very happy about that, and we’re looking forward to that process.”

Thompson’s term expired last December, but he had been expected to stay for the rest of this year, as called for under law when a successor has not been chosen.

In a brief statement confirming Thompson’s resignation, the Commerce Department said he was retiring and would pursue opportunities in the private sector.

Commerce Secretary Wilbur Ross thanked Thompson for his service but offered no explanation for his abrupt departure. No successor was announced, and the deputy director’s position is currently vacant.

Ross did highlight the importance of the succeeding at the decennial Census, even as the Bureau is losing its director and lacks a deputy.

“A complete and accurate Census is an important and monumental task, and your experience will be greatly missed,” Ross said of Thompson.

In an email obtained by HuffPost, Thompson told staffers that he was leaving now to give the Trump team time to select its own leader.

“I feel now is the right time for me to announce that I plan to retire on June 30,” the message said. It went on to express confidence that the Bureau will carry out what amounts to groundbreaking work in enumerating the national population.

“This will allow Secretary Ross and the current administration sufficient time to put in the proper leadership to guide the Census Bureau through the 2017 Economic Census, the 2020 Census and beyond,” Thompson said, referring also to the survey of some 4 million American businesses that goes into determining the nation’s economic health.

“A highly capable career management team is in place, and the next few years are critical for the agency,” Thompson said.

While the Commerce Department did not specify a reason for Thompson’s quitting, one source familiar with the matter said Ross had been unhappy with Thompson’s testimony last Wednesday.

Another source said an acting head would be chosen in the “coming days,” with a permanent selection made “in due course.”

A spokesman did not immediately answer questions about a meeting that Thompson and Ross had after the May 3 hearing. Thompson sent his resignation later Monday, the source said.

Census data is the key component in drawing congressional districts and in distributing hundreds of billions of federal dollars to states and localities. Businesses also depend heavily on the data for strategic planning.

The choice of who will lead the most important count of Americans now falls to the Trump administration.

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