The Cambridge, Mass., police sergeant who arrested Harvard University professor Henry Louis Gates last week is due to at a mid-day news conference being put together by a national police association, WCVB-TV reports.

Sgt. James Crowley told more of his side of the story this morning on WHDH-TV in Boston.

Gates, as has been widely reported, was arrested for disorderly conduct during an incident at his home. The professor accuses Crowley of racial bias (Gates is African-American; Crowley is white). Crowley says Gates became increasingly abusive and ignored warnings to stop.

President Barack Obama added to the attention the case is receiving when he said Wednesday night that Cambridge police acted "stupidly" when they arrested Gates.

Update at 12:27 p.m. ET: Obama was "dead wrong":

Police union attorney Alan McDonald just said the president was "dead wrong" when he said Cambridge police acted "stupidly" in arresting Gates. "Had professor Gates simply cooperated" with Crowley, McDonald said, the officer "could have cleared the matter" without any problem.

Update at 12:12 p.m. ET: The news conference has begun. Police union officials say Crowley will not be speaking, though he is there. Earlier, we wrote that he would be making some comments. We've edited the post above to reflect the fact that he's now not expected to speak, and updated the headline.

Sgt. Dennis O'Connor of the Cambridge Police Superior Officers Association just said that Obama, when he said police had acted "stupidly," used "the right adjective, but directed (it) to the wrong party." Presumably, he thinks the president should have said it was Gates who behaved wrongly. O'Connor said the president should apologize to the Cambridge department.