After a century of snootily looking down their noses at each other, are the US and European mainstream lefts linking up? Howard Dean, leader of the US Democratic Party, was the first-ever mainstream Democrat politician to address the congress of the Party of European Socialists, held last month in Portugal. Ségolène Royal from France, Romano Prodi from Italy, and a gathering of other centre-left prime ministers and party leaders sat as Dean made a classic social-democratic pitch for better wages, stronger labour rights, an end to wars and a united front to tackle global warming.
This was not the post-White House oratory used by Bill Clinton to schmooze Labour Party conferences, but a workaday appeal for formal links between the Democratic Party and its opposite numbers in Europe. Dean's call was reinforced by Nancy Pelosi, the new Democrat leader in the House of Representatives, who turned up unexpectedly at the seminar of European politicians in Washington and - in contrast to George W Bush - pledged to work with Europe on tackling climate change.
These attempts to reach out to Europe are filtering down to the smarter of the Washington top officials who are beginning to work on life after Bush and Cheney. European politicians have been surprised on visits to the state and defence departments at the friendly cries of: "We are all Europeanists now!" The Rumsfeld language of "old" (bad) western Europe and "new" (good) eastern Europe is no longer used.
The US is beginning to understand that its go-it-alone geopolitics have not worked. Making allies and friends means dumping Rumsfeld and John Bolton - the UN ambassador/bull who carried his own china shop around with him. America faces problems on too many fronts to want to alienate the one region in the world - united Europe - that shares a similar commitment to democracy, the rule of law, media freedom and laws trying to help the weak, the old, and men and women of different races, as well as gay people and the disabled.
Blah-blah about shared Atlantic values has existed for decades. But in the 20th century, the Europeans regarded the American left, including the Democratic Party and the trade unions, as irredeemably pro-capitalist and anti-socialist while, among the Democrats and in other US progressive movements, most had little interest in the doctrines of state ownership or pacts with communists that animated the post-1945 European left.
Now Europeans accept the market and Americans see their standard of living threatened by uncontrolled globalisation.
At the same time, the gap between rich and poor is opening up in a way not experienced for nearly a century. US trade-union leaders such as Andy Stern want to work with European labour to make modern capitalism less cocky and the response of the citizen as employee more confident. Stern's two-million-strong Service Employees International Union is trying new organising strategies that rely on Nordic-style partnership politics, rather than old leftist confrontation.
And, while Europe condemns Washington's foot-dragging over Kyoto, California is already passing environmental laws for the world's seventh-biggest economy which are way ahead of anything being tried in Europe.
For the first time in the history of European socialism, there is a realisation that the North American and European democratic lefts have more in common than the differences that kept them apart in the 20th century. Italy's combined left-wing parties are going the whole way and rebaptising themselves as the Democratic Party of Italy in conscious homage to their American cousins. The charismatic young female leader of the Danish Social Democrats, Helle Thorning-Schmidt, who happens to be Neil Kinnock's daughter-in-law, spoke after Dean at the European Socialist congress and called for a non-protectionist policy of support for workers hurt by globalisation.
As democratic-left parties around the world struggle to come up with policies for the 21st century, the opportunity for unity between progressives in the US and in Europe may have arrived.
Denis MacShane is a former minister for Europe