Sterling attended Carleton University and the University of Ottawa, and worked as a lawyer and engineer before entering public life. He was a partner in the Sterling & Young law firm, and in 1974 became President of the Manotick Home & School Association.
The Progressive Conservatives lost power following the 1985 election, although Sterling had no difficulty being re-elected in his own riding. There was another Progressive Conservative leadership convention in late 1985. On this occasion, Sterling broke with Timbrell (describing the latter's post-election opposition to Catholic school funding as an opportunistic volte-face), and supported Larry Grossman.
In the Liberallandslide of 1987, however, he was only able to defeat Liberal candidate Roly Armitage by about 500 votes in the redistributed riding of Carleton. To date, this was the only time in Sterling's career that his re-election was in doubt.
The Progressive Conservatives were defeated in the 2003 provincial election, although Sterling was able to defeat Liberal Marianne Wilkinson by about 6000 votes. He is currently his party's critic for Democratic Renewal.
In 2004, Sterling supported Jim Flaherty's unsuccessful bid to lead the Progressive Conservative Party.