Ontario's PC Transportation critic is calling on Dwight Duncan to resign as chair of the Windsor-Detroit Bridge Authority.
It follows a report by the Globe and Mail that Duncan made partisan social media comments disparaging U.S President Donald Trump and the federal and Ontario conservatives.
As chair of the bridge authority, the position is required to be non-partisan.
PC Transportation critical Michael Harris says after being caught abusing the integrity of the office, Duncan should do the honourable thing and resign.
In a letter from Duncan to federal Minister of infrastructure Amarjeet Sohi, Duncan "unreservedly apologizes".
He says he reviewed all 300+ postings going back to the date of his interim appointment and states "a number of my postings clearly violated the letter and spirit of Parliament's direction to Governor-in-Council appointees respecting partisan involvement while serving."
"Those postings have been or are being deleted today," he writes in the letter to the minister.
The authority is responsible for overseeing and building the new Gordie Howe International Bridge.