Welcome once again to the one-step forward, two-steps backward world of the 2010 census. With little more than six months before the start of the next count, the Census Bureau still doesn’t have a director. And on Tuesday, the bureau’s budget faces a crucial vote by House appropriators who must resist the temptation to shortchange the agency yet again.

The Obama administration inherited a Census Bureau that is ill prepared, after years of meddling and mismanagement, to conduct the upcoming count. In April, President Obama finally nominated Robert M. Groves, a top sociologist and survey expert, to lead the bureau, and in mid-May the Senate held Mr. Groves’s confirmation hearing. At long last  and not a moment too soon  the census seemed to be getting back on track.

More than three weeks later, Mr. Groves has yet to be confirmed. He is the latest target of an unexplained hold by one or more anonymous Republican senators. (Under recent Senate rule changes, it’s hard but not impossible to keep such a hold going for several weeks.) If it endures, it would take 60 votes to confirm Mr. Groves.

It is hard to imagine the public interest that is being served by the hold. It is easy, unfortunately, to imagine the political interest. A leaderless Census Bureau is unlikely to pull off an accurate count. Inaccurate tallies tend to favor Republicans, because a bad census misses hard-to-count groups that tilt Democratic, like minorities and immigrants, thus over-representing easy-to-count suburbanites who tilt Republican.