She was a member of the Legislative Assembly of Ontario from 1995 to 2003, and was a senior cabinet minister in the governments of Mike Harris and Ernie Eves.
She worked as a Government Relations Consultant with Public Affairs Management from 1987 to 1991, and was Director of Policy for the College of Physicians and Surgeons of Ontario from 1991 to 1995.
In 2001, Flaherty announced that the government planned to introduce a tax credit for parents choosing to send their children to private and denominational schools.
As a result of this controversy, Ecker became a leading spokesperson for "moderate conservative" positions in her party, against the right-wing views of Flaherty and Harris.
[6] Shortly after being named as Finance Minister, Ecker announced that the Eves government would postpone the previously-announced private-school tax credit.
[citation needed] Ecker also introduced the Eves government's Keeping the Promise for a Strong Economy Act (Budget Measures), 2002.
In 2003, Ecker delivered her provincial budget at an auto parts factory owned by Magna International, rather than in the legislature.
[10] She supported Christine Elliott (spouse of Jim Flaherty) during the 2009 Progressive Conservative Party of Ontario leadership election and served as her campaign chair.