In the 1996 federal election she contested the newly created seat of Namadgi against the Liberal Member for Canberra, Brendan Smyth.

However, due to the heavy swing nationwide against the Keating government, Ellis was only assured of victory when she received a large flow of Green preferences on the third count.

[1] Ellis become one of the few Labor candidates to defeat a Liberal during the landslide election that brought the Howard government to power.

[3] She was re-elected in November 2007—with an increased majority—in the election that returned Labor to power federally under new Prime Minister Kevin Rudd.

She is a leading member of the ACT right wing Labor caucus, Centre Coalition.