[1] Mulder was born in Colac, and attended Trinity College, but did not complete high school and began working as a laborer.
[2] Mulder joined the Liberal Party in 1992, and was an active member of his local branch thereafter, serving as its vice-president from 1993 to 1995 and president from 1995 to 1999.
He subsequently won preselection to contest the safe seat of Polwarth upon the resignation of long-serving Ian Smith.
As Shadow Minister for Transport, Mulder became one of the highest-profile members of the opposition, leading attacks on cost blow-outs over the Regional Fast Rail project and the rebuilding of Spencer Street station, the badly delayed Craigieburn railway line extension[5] and the controversial siting of the Marshall railway station.
With the party continuing to generally struggle, however, Mulder began to be seen as a potential replacement for leader Robert Doyle.