Again, this is not a real issue. It's an issue driven by the paranoid GOP base. The census has not been removed from the Commerce Department's purview, as Ambers explains below. And past censuses have long been conducted with coordination from the White House staff:

“As they have in the past, White House senior management will work closely with the Census Director given the number of decisions that will need to reach the President’s desk," White House spokesman Ben LaBolt said in a written statement. "This administration has not proposed removing the Census from the Department of Commerce and the same Congressional committees that had oversight during the previous administration will retain that authority.” ...

Kenneth Prewitt, who served as Census director from 1998 to 2001, said he worked with White House staff during the 2000 Census on budgeting, advertising and outreach efforts

... Other former Census directors agreed that coordination with the White House on budgeting and outreach was appropriate while data collection and analysis should be kept separate. As for potential political interference, “It’s virtually impossible to do something wrong without someone finding out about it,” said Vincent P. Barabba, who ran the 1980 Census. “It’s about as transparent an agency that exists.”

This issue was championed by Republicans for the usual "the-darkies-are-taking-over!" reasons. And Gregg's broad support for the kind of stimulus bill Obama has just got through the conference is a matter of public record. So the real reason for Gregg's departure is that he simply couldn't handle the backlash from his own party for providing bipartisan cover for Obamanomics. I guess they believe that assaulting the new president as he tries to reach out is their ticket for future relevance. Hello to all this ...