Wirthlin, a professor of economics and statistics, founded his own opinion research firm Decision/Making/Information, which later became Wirthlin Worldwide.

He is best known for his work as strategist and pollster to Ronald Reagan. Wirthlin came on board while Reagan was governor of California and ran polling for his unsuccessful bid for the Republican presidential nomination in 1976, before serving as campaign director for Reagan’s two presidential election victories in 1980 and 1984. Reagan once said of Wirthlin: “When he speaks, I listen.”

In 2004 Wirthlin published a book about his work with Reagan, entitled The Greatest Communicator: What Ronald Reagan Taught Me About Politics, Leadership and Life.

Outside the US, he served as an adviser and pollster to Margaret Thatcher, German Chancellor Helmut Kohl and Israeli Prime Minister Benjamin Netanyahu.

Wirthlin Worldwide was acquired by Harris Interactive in 2004. Wirthlin served on the board of directors at Harris until his retirement in 2007. He was described at the time by Harris’s then CEO Greg Novak as “one of the legends of market research”.

He won Advertising Age’s Ad Man of the Year Award in 1981, the American Association of Political Consultants’ Pollster of the Year Award in 2000 and its Lifetime Achievement Award for a Republican in 2009. His company had twice won the Grand Prize at the Advertising Research Foundation’s David Ogilvy Research Awards, in 1999 and 2002.

His son Richard L Wirthlin said yesterday: “We are grateful for our father’s life, love, example and heritage of faith… We will greatly miss him until we are together once again.”

Jim Granger, former CEO of Wirthlin Worldwide, said: “He was both a leader and a doer, indefatigable, always moving forward. Like his friend and favourite client Ronald Reagan, he was both strong and gentle.”

Dee Allsop, another former chief executive of the company, went on to set up Heart + Mind Strategies, which describes itself as a “Wirthlin-inspired consultancy”. Allsop called him “one of the true giants of strategic communications and research”.

Wirthlin was survived by his wife Jeralie Mae Chandler, eight children, 27 grandchildren and six great-grandchildren.