It happened to the Bush EPA-nominee Stephen Johnson.
From Inside EPA today:
Republican senators could use the confirmation hearings for Jackson’s replacement to reiterate their long-running concerns over EPA’s policies developed during Obama’s first term. They might also use the confirmation hearing to try and win concessions from the next administrator on key policy goals, a strategy that both Democratic and Republican senators on the environment panel have used for previous EPA confirmation processes.
For example, in April 2005 Sens. Boxer and Bill Nelson (D-FL) placed a hold on then acting EPA Administrator Stephen Johnson’s nomination as permanent agency chief. The senators did not lift the hold until the nominee announced that he was canceling plans to conduct a controversial agency study on the impacts of pesticides on children that the lawmakers had criticized…
Will testing diesel exhaust on children warrant the same treatment?