Vincent P. Barabba, a member of the California Citizens Redistricting Commission, was census director from 1973 to 1976 and from 1979 to 1981. Kenneth Prewitt, a professor at Columbia University, was census director from 1998 to 2001.

The census, one of the most important activities our government undertakes, is under threat by uncertain funding and a leadership vacuum at a crucial moment. As former directors of the U.S. Census Bureau, serving in both Republican and Democratic administrations, we urge President Trump to act swiftly and the Senate to cooperate in naming a new director as the 2020 Census nears.

The immediate task is to nominate someone who can provide stability through the final years of the decade, explain the importance of the agency’s mission compellingly, address Congress’s fiscal concerns and be ready for full immersion in the important tasks at hand.

Equally important is a serious increase in funding for next year, ramping up further in 2019. This is a critical period in which to begin operations, including well-researched advertising messages, staffing and training an army of temporary workers, opening field offices and testing new technology. The Census Bureau cannot do any of this at the last minute, just as the Defense Department cannot prepare for military action when a threat is imminent.

The decennial census — the once- a-decade effort to count every person living in the United States — is an enormous and complex task. It is specifically required by the U.S. Constitution because it is essential to our representative government. Census data will be used to determine how many U.S. representatives each state gets and to draw voting districts for the House, state legislatures, city councils and school boards.

More than $600 billion a year for vital services such as highway construction, low-income energy assistance, maternal and child health, and food assistance flows to states and communities based on census-derived data. Nonprofit agencies and businesses rely on census data to evaluate population trends and community conditions and to target their services and investments effectively.

The Census Bureau is in the critical phase of preparing for its “dress rehearsal.” It must occur on schedule, and it must be robust enough to thoroughly test procedures new to Census 2020. These include the first-ever option to respond to the census online and to equip census takers with Internet-connected devices to save time and dramatically cut paperwork.

New procedures and technology — deployed for the first time from start to finish — will have glitches that can be fixed if found in 2018, but that opportunity will rapidly pass, even if sufficient funds are provided. The Air Force does not send a new fighter plane directly from the assembly line to the front lines, skipping the test phase. Neither should we expect the census to field new procedures without thorough testing.

The 2020 Census faces unprecedented challenges in collecting data, including fear of government authorities in immigrant communities, cybersecurity threats (real or perceived) and uneven access to reliable Internet service, which could disadvantage rural, low-income and older households. The nation needs a Census Bureau director with the capabilities to navigate these minefields credibly and deliberately. He or she must have the confidence of public officials from both sides of the political aisle, at all levels of government, as well as the confidence of the American public.

In 2011, Congress passed a law that requires the census director to “have a demonstrated ability in managing large organizations and experience in the collection, analysis and use of statistical data.” The law calls for the director to serve a renewable five-year term to ensure continuity in planning and operations and to help make the Census Bureau effective, accountable and less susceptible to partisan pressures. In fact, the law specifically calls for the nomination of a candidate “without regard to political affiliation,” signaling that the census director’s objectivity is vital to ensuring confidence in the agency’s statistics and methods.

It is encouraging that Commerce Secretary Wilbur Ross appointed interim leaders for the Census Bureau from among the agency’s dedicated, experienced career staff. But they cannot wield the credibility and influence that a permanent director can have across the administration and before Congress and the American people.

There will be no second chance to get the 2020 Census right. Delayed funding cannot make up for preparation that should already be underway. We will all live with the results for a decade. The health of our democracy — and the well-being of individuals, families and communities — requires our elected leaders to find common ground and serve the common good. Identifying, nominating and confirming a qualified, trustworthy director for the U.S. Census Bureau must be a top priority for administration and Senate leaders.