PENN KEMBLE was an influential figure on the American political scene for more than 30 years. Though cited on many a web page as a Cold Warrior, he had friends among those ranging from traditional labour leaders to neoconservatives.

He is best known, on the one hand, for his publicity on behalf of the Nicaraguan Contras (counter-revolutionaries) and, arising from this, for his part in the Iran-Contra scandal during Ronald Reagan's Republican Administration in the 1980s. On the other hand, his most senior positions were as deputy director and acting director of the United States Information Agency during the Democrat presidency of Bill Clinton.

The surprising contrast between these roles is a clue to Kemble's individuality — and to the problem of assigning a label to him. He rejected the description of neoconservative, which close colleagues such as Joshua Muravchik, of the American Enterprise Institute, have been proud to adopt.

To the end of his career, Kemble balanced his criticisms of what he saw as disastrous New Left tendencies among the Democrats with the — to him — equally damaging thinking of the New Right. He believed in the civilising role of government in domestic politics, and in the need to promote democracy internationally.

Kemble was an inveterate political entrepreneur, constantly engaged in a world of single issue committees, policy initatives, think-tanks and political campaigns. He was a lifelong Democratic Party and labour union activist, although much of his international work was bipartisan.

That he could build a successful career out of a series of soft-funded ventures and of temporary political appointments is typical of US politics, and especially of the world of formerly leftist New York policy intellectuals among whom he found his spiritual base. Before he migrated in 1972 to Washington, he was an unusual figure on this New York scene.

Richard Penn Kemble was not a New Yorker, having been born in Massachusetts, raised in Pennsylvania and educated in Colorado. He was neither Jewish nor Catholic. He was a polished, dapper figure in a milieu of scruffy, urban debaters, philosophers and schemers.

But he was at home among such political intellectuals as Daniel Patrick Moynihan, Norman Podhoretz, Sidney Hook and Bayard Rustin. The essence of New York intellectual politics was its mixture of discussions about ideas, and a taste for propaganda, publications, manifestos, declarations, factions and plots.

In his undergraduate days in Colorado, Kemble helped to set up the Colorado chapter of the Young People's Socialist League. He then lost his job at The New York Times when he refused to cross a picket line of striking typesetters in an expression of his deep commitment to organised labour, which he retained throughout his life. In 1972 he was a founder of Social Democrats, USA, a body sometimes compared to the Fabian Society in the UK.

The crushing defeat of George S. McGovern, who was chosen as the Democrat nominee on a leftist ticket in the presidential election campaign of 1972, convinced Kemble of the vital need for the Democratic Party to stick to its blue- collar base and to the centrist political tradition of Hubert Humphrey. In the vain attempt to win the Democrats to this aim, he was a founder of the Coalition for a Democratic Majority, serving as chair of its executive from 1972 to 1976. He was a special assistant and speechwriter for Senator Moynihan in 1978-79.

Like others who worked with Senator Henry “Scoop” Jackson in the Coalition for a Democratic Majority (including Jeane Kirkpatrick and Richard Perle), Kemble turned his attention in the 1970s to the Soviet threat. In an effort to combat support for nuclear disarmament by Western nations within the World Council of Churches, Kemble helped in 1981 to set up the Institute on Religion and Democracy. He worked from 1981 to 1988 as president of Prodemca (the Committee for Democracy in Central America), an organisation created to combat the influence of the Sandinistas in Nicaragua and of other forces in Central America which he saw as pro-Communist and anti-democratic.

In 1991 he was appointed by President George Bush to the Board for International Broadcasting, which for many years directed broadcasting to Central Europe and countries of the former Soviet Union with funds from the US Government. He was also Washington representative for the New York-based non-governmental organisation, Freedom House. These activities paved the way for his appointment in 1993 by President Clinton to high office in the US Information Agency.

From 2001 his strong Democrat loyalties precluded him from taking office under President George W. Bush, though he did serve in 2002 as chairman of a team of eminent persons appointed by the Secretary of State, Colin Powell, to investigate the survival of slavery, abduction and forced servitude in Sudan. Remaining as active as ever, he became a Senior Fellow at Freedom House, where he spearheaded a project to promote a transatlantic network of democrats who would co-operate in promoting democracy in the Middle East.

With his wife, he set up the Foundation for Democratic Education. They worked closely with British trade unionists to develop a US approach to lifelong learning, which they considered essential in an era of globalisation. During and after the Clinton Administration, Kemble also was closely involved in the Community of Democracies Initiative.

Kemble was a notable cook of barbecued salmon, a player of handball even during his final struggle with a brain tumour, and an activist in Social Democrats USA until his last days.

He is survived by his wife, Marie-Louise (Mal) Caravatti.

Penn Kemble, political activist, was born on January 21, 1941. He died on October 15, 2005, aged 64.