Jessica Simpson sang "God Bless America" joined by First Lady Michelle Obama and Jill Biden, wife of Vice President Joe Biden, last night at Denver's Coors Field before a Rockies vs. Mets game held to entertain military families. The singer was apparently handpicked by the first lady for the show, despite any political differences — Jessica was well known as a favorite of former president George Bush. The event was also a chance for Michelle and Jill to kick off their new Joining Forces initiative, which aspires to help soldiers and their loved ones deal with long separations. It was a humbling honor for the star. Jessica Simpson tweeted, "It's such an honor to join First Lady Michelle Obama as she kicks off her new initiative in support of our military & their families."