Michelle Ballantyne, leader of the Conservative group on Scottish Borders Council, was sworn in as a South of Scotland MSP at Holyrood on Tuesday.
However, the mother-of- six says she is keeping her options open about how long she will remain at Newtown as an elected member for the Selkirkshire ward.
“Things have happened so quickly and, with regard to Holyrood, quite unexpectedly,” she said.
“While I am delighted to become an MSP, I feel I still have a duty to my constituents in Selkirkshire, so I will continue to exercise the dual mandate, which allows me to be both a councillor and an MSP at the same time, for the immediate future.
“I would like to see the new ruling administration my party has formed with the independents on the council a chance to bed down and become established, so I am keeping my options open regarding the exact time of my departure.”
Mrs Ballantyne said she would donate her councillor’s salary – just under £17,000 a year – to charity until she gives up the council.
When that happens a by-election will be held in Selkirkshire to decide who will replace her at Newtown.