Quality time on the trail

Maybe it's an indication of the high stakes in Tuesday's Pennsylvania primary. Or maybe they just want to actually see each other on the campaign trail.

Whatever the case, it's interesting to note that both the Clintons and the Obamas are making unusual joint appearances today.

Hillary and Bill Clinton are both at a rally in Pittsburgh this afternoon, and are scheduled to be joined by daughter Chelsea for another event tonight at the University of Pennsylvania in Philadelphia to wrap up their primary-eve campaigning.

Barack and Michelle Obama are to be together at two events tonight, one a town hall meeting in McKeesport and the other a rally at the University of Pittsburgh's basketball arena.

In recent weeks, the couples have campaigned separately so they can cover more ground and pitch more voters.