The Miliband and Alexander double act is not just for show. They are deeply worried by the warfare that has wracked their Labour Party in recent weeks. Three weeks ago a mutiny by once loyal M.P.s forced Blair to announce that he would give way to Brown by next summer. But the wrangling has continued as factions battle for control of the policy agenda between now and Blair’s exit. Last week, during a tense cabinet meeting, ministers warned that power struggles were turning off the public. “This must stop,” one reportedly said. As the party gathers in Manchester for this week’s annual conference–Blair’s last as leader–harmony is the watchword. What Labour needs, says party chair Hazel Blears, is “not just a show of unity but to be united, seriously, from the top to the bottom of the party.”

That’s a tough ask. Even with Blair and Brown in ceasefire mode, senior politicians who are losing their grip on power have kept the infighting alive. Some, like Leader of the House of Commons Jack Straw, 60, have been careful to maintain good relations with Brown. Others, like Home Secretary John Reid, 59, and Education Secretary Alan Johnson, 56, are hanging back as possible challengers to the chancellor if he stumbles. Brown is further embattled by what Sunder Katwala of the Fabian Society calls the “Blairite Kamikaze Squadron,” including former Cabinet ministers Alan Milburn and Stephen Byers, who have no prospects in a Brown government. Compounding the troubles, voters increasingly believe the 39-year-old Conservative leader David Cameron would make a more effective, enthusiastic and likable P.M. than Brown, according to last week’s Guardian poll.

Amid the tumult, the challenge of unifying the party falls largely on the shoulders of New Labour’s “second generation,” a phrase Miliband and Alexander use in an article they co-wrote this week. It refers to politicians in their 30s and early 40s who must look beyond both Blair and Brown to the day when they will rule the party. Never mind that the article itself is a bland mini-manifesto for “new” New Labour–a post-Blair, post-Brown platform. (The buzz phrase, borrowed from former U.S. president Bill Clinton, is “economics plus”–“economics plus communications, plus travel, plus immigration, plus a sense of the new ways in which people around the globe live their lives.”) The important point is that the two brightest sparks of the party, representing two warring factions, wrote it together. And didn’t stab each other in the back.

The face of this new generation is indeed very different. Blair and Brown rose from distinctly disparate backgrounds, to a degree mirroring Britain’s traditional social divide between upper and working classes. Labour’s emerging young leaders share a much more integrated worldview. If their elders were shaped by the cold war and pitched battles between government and the unions–Thatcherism versus old Labour–theirs is a world of globalization, immigration and free markets. Labourites who fear their party will somehow re-treat to the past under Brown need only look at the young people around him for reassurance.

Consider Miliband. Often described as a prime minister in waiting, he’s currently rift healer in chief. Asked last week if he objected to being called “a Blairite for Brown,” he said: “There are much ruder things they can say about you.” He knows whereof he speaks: his younger brother Ed, 36, also an M.P., is a former Brown aide and a member of the chancellor’s brain trust. Like many second-generation illuminati, they both read P.P.E. (philosophy, politics and economics) at Oxford and went on to study in America. David was a Kennedy scholar at MIT and Ed studied at Harvard’s John F. Kennedy School of Government, as did Alexander, who had read politics at the University of Edinburgh. Before running for office, their tracks through government were separate but similar. David ran Blair’s policy unit. Ed and Alexander worked for Brown.

They are now in the wings, waiting–Miliband as Environment secretary, Alexander as Transport secretary. Ed Miliband is a minister in the Cabinet Office. His senior sidekick, Ed Balls, 39, who also was a Kennedy School scholar, is among Brown’s closest advisers. And so it goes elsewhere in the senior ranks. Ruth Kelly, 38, Communities and Local Government secretary (P.P.E., Oxford), worked for Brown. James Purnell, 36, Pensions minister (P.P.E., Oxford), worked for Blair. Liam Byrne, 35, Home Office junior minister (Fulbright scholar, Harvard Business School), also worked for Blair. Above all, they share a common goal: to ensure that the party they will inherit does not destroy itself. Says Miliband: “We’re not going to waste the opportunity to shape the country.”

The Milibands of the world won’t be changing much of anything for a while. But when their time comes round, “intergenerational justice” will be big. That’s the notion, as Miliband and Alexander put it in their article, that the young should get as much attention as the elderly. (Think education.) Immigration will be a hot-button issue, as will the environment.

Little of this will be on Labour’s agenda as the party convenes this week. Mostly, the party wants merely to hang together and win the next election, probably in 2009. Hazel Blears doesn’t mince words: “For me, this test is whether we’ve got the ‘governing gene’ in our DNA. Do we really believe that Labour can be the natural party of government, or do we think that basically Tories rule but we come in every now and then as a bit of a change?” One thing she knows, like Miliband and Alexander and other rift healers: Labour won’t pass the gene test if it tears itself apart.