National Journal has the story:
Just as the dust was settling last week from the exits of Tom Daschle and Nancy Killefer, Sen. Judd Gregg, R-N.H., whipped up the tumult again. By pulling out of consideration for Commerce secretary, a post previously abandoned by New Mexico Gov. Bill Richardson (D), Gregg became the Obama administration's fourth high-level dropout so far.
But while this administration has set a turnover record for an incoming Cabinet, it's hardly the first to run into problems with its nominees. Bill Clinton leads among recent presidents with a total of six major nominee dropouts over the course of his presidency, followed by George W. Bush and his Cabinet's two withdrawals. Three previous presidents -- George H.W. Bush, Ronald Reagan and Jimmy Carter -- each slipped once. All but Reagan had at least one kink in their first-term Cabinet selection process, with Clinton accepting three withdrawals.
I'm not sure this is a fair accounting of the process; it counts Tim Geithner as a successful nomination - which is rather generous. If Geithner were considered a failed nominee, Obama would be just one more Commerce Secretary Nominee away from Clinton's record, and could still break it with a Daschle-like nomination at HHS.