David Valentin is a principal at Liaison Strategies. Valentin is a nationally recognized pollster and lobbyist who works with a variety of nonprofits across Canada including the National Ethnic Press and Media Council of Canada and the Canadian Civil Liberties Association. He is a member of the Canadian Research Insights Council.

In 2013, Valentin co-founded Mainstreet Research, a polling firm. Within a year, Mainstreet signed a contract with Postmedia Network, Canada's largest newspaper chain, to provide public facing market research, covering everything from vaccination studies to political polling including election surveys. In 2018, Valentin departed Mainstreet to found Focus on Research, a boutique polling firm, and Liaison Strategies, a government relations and public relations shop.

Valentin is a nationally recognized pollster who has made over 400 media appearances and has been seen on CBC, CTV, Global News, the Globe and Mail, the Toronto Star, CP24 and more. He has worked closely with researchers and professors at the University of Toronto and Concordia University. He resides in Toronto and speaks English, Spanish and intermediate French.