Democrats and Republicans will this morning release their separate plans to raise the debt ceiling before the August 2 deadline. But only one plan can pass and Congress is running out of time. The lack of time has thrown a spotlight on the 14th amendment, which some say would allow President Obama to increase the debt ceiling on his own.   Larry Tribe, a professor of constitutional law at Harvard Law School, discusses the constitutionality of the 14th amendment in the debt ceiling debate.