Talk about irony: Earlier in the campaign, when Hillary Clinton pointed out that pledged delegates were not actually required to vote for the candidate they're pledged to, and an unnamed person in her campaign said the Clinton camp might seek to woo some of Barack Obama's pledged delegates, the political world was sent into a tizzy. Clinton's campaign had to come out and deny it had any intention of poaching Obama's pledged delegates. And now, one delegate pledged to Clinton has announced that, at the Democratic convention this summer, he'll vote for Obama.

In a sign of the times, though, there's no indication the Obama camp had to approach Jack Johnson for him to change his vote. Johnson, the county executive in Prince George's County, Md., had endorsed Clinton in February -- after allowing his name to be included in a list of Obama supporters only two months before -- and was selected as a pledged delegate by the Maryland Democratic State Central Committee, with input from the Clinton campaign. "I cannot in good conscience go to the convention and not support Barack," Johnson told the Washington Post. Clinton "ran a great campaign, but she fell short of the line."

Johnson also says he'll ask Maryland Gov. Martin O'Malley and Maryland Sen. Barbara Mikulski, both Clinton supporters, to release the state's other elected Clinton delegates from their pledges to support her. Neither has shown any indication they'd be likely to do so, at least not yet.

Separately, as of Tuesday morning, Obama had already picked up four superdelegate endorsements for the day. The new support came from Rep. Joe Donnelly, D-Ind.; New Orleans Mayor Ray Nagin; Anita Bonds, chairwoman of the D.C. Democratic Party; and Roy Romer, the former governor of Colorado, who is also a former chairman of the Democratic National Committee.