From NBC's Ken Strickland:

Republican Sen. Judd Gregg, who withdrew as President Barack Obama's nominee for commerce secretary in early 2009, told NBC News that he “could have worked for the Clinton administration” but could “never be comfortable” with the Obama administration’s agenda.

Gregg says Clinton and his politics were "centrist." But after 18 months of interaction with the Obama administration, Gregg said that the current president’s brain trust has “an ideological purpose."

“If I had worked for this administration I would have been totally out of sync very quickly, because this administration has a very ideological purpose,” he said. “I respect that; it's their view. But I could never be comfortable with it and agree with it.”

(It’s worth noting that Gregg has not always spoken highly of the 42nd president. In a 1993 interview with New Hampshire’s Union Leader newspaper, for example, Gregg said Clinton’s economic plan would “reestablish government as the dominant force in the economy and in social policy,” labeled his tax program “class warfare,” and groused that the president “made no attempt to involve any Republicans” in its formulation. He also voted “guilty” during President Clinton’s impeachment trial in 1999.)

Asked what advice he would offer colleagues who considering working for an administration of the opposite party, Gregg noted that some cabinet jobs are less prone to partisan politics than others.

“There are certain jobs which it doesn't matter what your ideological issues are. Most of the foreign policy issues are not,” he said.

“You could put a real hard-core conservative -- as this president has, theoretically, in [Afghan war commander David] Petraeus and [Defense Secretary Robert] Gates - in positions that have nothing to do with politics, which are national defense or international issues,” Gregg added.

Read the whole transcript of Gregg’s conversation with NBC News here.

NBC's Ken Strickland sat down with nine senators departing the upper chamber this year. He asked Evan Bayh, Robert Bennett, Sam Brownback, Kit Bond, Jim Bunning, Chris Dodd, Byron Dorgan, Judd Gregg, and George Voinovich the same eight questions and a wildcard query. This excerpt was taken from the transcript of that interview. Additional reporting can be found on politics.msnbc.com.