US Democratic presidential candidate Senator Hillary Clinton (D-NY) (R) walks with her traveling chief-of-staff Huma Abedin as they approach a group of police officers after cancelling a rally in Fort Worth, Texas February 22, 2008. A Dallas police officer was killed Friday when his motorcycle struck a pillar as he was escorting democratic presidential candidate Senator Clinton to a rally in Dallas. Clinton cancelled the rally in Forth Worth, saying it would be inappropriate to hold a rally in light of the tragic circumstances.