[1][6][7] Stewart was initially a "long-time" member of the National Party and acted as secretary for the Feilding branch 1987–90.
[1] Stewart was re-elected on the New Zealand First party list in the 2005 general election, having lost in Piako.
The bill followed the 1999 New Zealand MP reduction referendum, in which 81.46% of participating electors voted to reduce the number of MPs to 99.
She was promoted to fifth on the New Zealand First list, but the party lost all its parliamentary seats, winning no electorates and polling below the 5% threshold.
[14] At the 2011 election Stewart was re-elected to Parliament following a resurgence in the New Zealand First vote, where she had been ranked fifth on the party list.
Stewart had stood again in the Waikato seat but was unsuccessful in defeating Lindsay Tisch, the incumbent National Party of New Zealand MP.
[17] Stewart was successful in having two health-related private member's bills selected for introduction during her second period in Parliament, though neither passed.
[18] The bill proposed that over 65s who receive New Zealand superannuation would be eligible for three free doctors' visits per year.
[24] Stewart announced that, following the death of her husband on 31 January 2017, she would not stand for re-election in the 2017 general election.
[5] In her valedictory statement on 8 August 2017, she stated that she considered her greatest achievement to be working with Labour's health minister Pete Hodgson on providing free doctors' visits for children under six.