Slater joined the firm in 2007 and will now be responsible for overseeing all domestic and international research, as well as the company’s Sun Surveys call centre.

Baumann has also been with the firm since 2007 and specialises in US campaigns and political issues. Lieberman joined in 2006 after managing several election cycles for the Democratic Congressional Campaign Committee (DCCC).

Egelsky joined the company as an intern in 1998 and will provide analysis and strategy in the areas of US political campaigns and issue advocacy.

Stan Greenberg, the firm’s chairman and CEO said: “Baumann, Egelsky, Lieberman and Slater continue in their new positions with a high level of expertise and understanding. They are tested and experienced. All are a representation of our firm’s growth.”