Publicly, Republicans attribute their opposition to Groves to his statistical expertise and his history at the Census Bureau. While an associate director at the bureau in the early 1990s, Groves advocated the use of his specialty, statistical sampling, which can be used to compensate for undercounted demographics, such as illegal immigrants and the poor. (Republicans have effectively prevented census sampling for decades.) But in his confirmation hearings earlier this year, Groves promised not to use sampling. And Commerce Secretary Gary Locke--whose department oversees the census--noted that the Supreme Court had rejected sampling as a method to determine Congressional district reapportionment (though it left unclear whether the method could be used to determine redistricting or federal funding for states).
Yet, despite Groves' pledge, Shelby and Vitter have maintained the hold for nearly two months. At least one prominent Republican senator, Susan Collins of Maine, has spoken out in favor of Obama's nominee. "I do not know who has placed a hold on Mr. Groves' nomination, nor do I understand the rationale for holding him up," she told the Associated Press in June. "I am very eager to get this qualified candidate on the job." Collins is the ranking Republican on the Senate Homeland Security Committee, which considered Groves' nomination.