If you're interested in another 30-minute argument about health care mandates, followed by one more round on the 2002 Congressional vote authorizing the use of force in Iraq, you're in luck: the two remaining Democratic presidential candidates will be holding another primary debate.

That would be their 21st one.

Today Sens. Hillary Rodham Clinton (D-N.Y.) and Barack Obama (D-Ill.) announced that they had agreed to participate in a nationally televised debate in Philadelphia on April 16, in advance of Pennsylvania's April 22 primary. The debate will be hosted by ABC News and is sure to see the candidates covering familiar ground, as well as any matters that have cropped up since what many thought would be their final debate, held in Cleveland, at the end of February.

Obama has also accepted an invitation to participate in a debate hosted by CBS News in North Carolina on April 19, in advance of that state's May 6 Democratic primary, moderated by Katie Couric and Bob Schieffer.

"Senator Obama welcomes the opportunity to openly debate Senator Clinton on the issues important to Americans in North Carolina and Pennsylvania and hopes that she will accept these invitations as well," said Obama campaign spokesman Bill Burton in a statement.

No word yet from the Clinton camp on this one.

By Garance Franke-Ruta, The Washington Post, March 13, 2008