Sen. Edward Kennedy (Mass.), who has been fighting brain cancer, will once again look to galvanize fellow Democrats when he whisks into Denver tonight to surprise the party and appear at the crowded convention hall. Kennedy, who was diagnosed with a tumor this spring, has been undergoing treatment in Massachusetts since May. Since then, the second-longest-serving Democratic Senator has largely stayed away from his legislative duties but stunned colleagues when he dashed into the chamber to cast the deciding Medicare vote in June. In a statement, Kennedy’s office said: “Sen. Kennedy is in Denver and plans to attend tonight’s tribute to him. He’s truly humbled by the outpouring of support and wouldn’t miss it for anything in the world.” Kennedy has been an ardent supporter of Sen. Barack Obama’s (Ill.) presidential bid, and his endorsement signaled the beginning of the Democratic establishment’s backing of the presumptive nominee earlier this year.