U.S. Rep. Chris Van Hollen (D-Md.), the chair of the Democratic Congressional Campaign Committee, appeared onstage at the party's national convention in Denver Tuesday, bringing eight Congressional hopefuls along with him.

Van Hollen said it wasn't enough for Democrats to elect U.S. Sen. Barack Obama (D-Ill.) to the White House; they had to expand their majority in Congress, he said. 

Among those Democratic challengers who appeared with Van Hollen was Jared Polis, who is seeking Colorado's 2nd Congressional District seat, which is being vacated by U.S. Rep. Mark Udall.