The cause of 69-year-old's death was a heart attack on Monday, according to a statement by his consulting firm, Polyconomics of Parsippany.

Wanniski coined the phrase "supply-side economics", referring to a theory that cutting personal income tax rates would lead to increased investment and create economic growth.

A former editorial writer at The Wall Street Journal, Wanniski and several other conservative thinkers pushed their theory in the face of other conservatives' strong resistance to deficit spending.

Wanniski advised several Republican political candidates. He was asked to resign from the Journal in 1978 after a supervisor saw him at a train station passing out fliers for a Republican US Senate candidate.

Influential writer

He wrote the book The Way the World Works that same year, and it became a favourite of some economic conservatives for its condemnation of taxes.

The National Review cited the book as one of the 100 most influential of the 20th century.

Wanniski briefly advised Reagan's presidential campaign and later served in a similar capacity for the presidential bids of Bob Dole and Steve Forbes.

In 1981, with Reagan as president, Congress went on to pass the one of the largest-ever cuts in taxes on income and capital gains.

He had been a regular contributor to’s opinion section.  Wanniski stood against the Iraq war and had argued that the perceived threat from Saddam Hussein's "weapons of mass destruction" was exaggerated.

Early on in his career he reported for the Las Vegas Review-Journal before joining a now-defunct newsweekly, the National Observer, in Washington in 1965.

Wanniski was born in Pottsville, Pennsylvania, on June 17, 1936. He is survived by his wife, three children, his mother; a sister, a brother and a granddaughter.