Kennedy poised to endorse Obama Key Democratic nod a setback for Clinton By Susan Milligan, Globe Staff | January 28, 2008WASHINGTON - Senator Barack Obama will collect the endorsement of Senator Edward M. Kennedy today, winning the support of a powerful icon of the liberal Democratic establishment as Obama challenges Senator Hillary Clinton before the crucial Super Tuesday showdown on Feb. 5.Kennedy confidants said Massachusetts' senior senator will appear this morning with Obama and Kennedy's niece, Caroline Kennedy, at a rally at American University in Washington to announce his support. Their joint appearance will suggest Obama's claim to the mantle...