Third-Party Contender: Liberal Democrat Nick Clegg

To appreciate how surprising it is that Nick Clegg, the personable leader of Britain's Liberal Democrats, could be poised to become one of Britain's most powerful politicians after national elections tipped for May 6, it's necessary to understand something of Middle England. Defined by attitude, not geographical location, the country's heartland is inhabited by small-c conservatives and big-E Euroskeptics, people unsettled by rapid social change and radical ideas. Such voters, historically decisive in U.K. polls, tend to view liberals and urban sophisticates with deep suspicion, and might be expected to react to the profoundly liberal, unambiguously sophisticated Clegg with all the enthusiasm of vampires invited to dunk their French fries in aioli.

Clegg, 43 and fresh-faced, has led Britain's third party since 2007. He is multinational (his mother is Dutch; his father half Russian) and multilingual (he speaks five languages). A supporter of the European Union, he worked first at the European Commission, then as a member of the European Parliament, until he gave up being an MEP in 2004 because the traveling undermined his family life. He's a new man, and if he looks a little bleary it's probably because he's been woken by his young sons or risen early to take his wife, a high-powered attorney, to the airport. His liberalism is the kind that prizes civil liberties and equality of opportunity, and repudiates vested interests, even when they come in the shape of venerable institutions. That includes his determination to overhaul Britain's "19th century, very male, very uncontemporary" political system. (See pictures of 20th Century Britain.)

Add to this Clegg's fervent allegiance to a liberal movement that hasn't led a government since World War I and you have some idea of how distant the gates of Downing Street might appear. Yet Britain's battered Prime Minister Gordon Brown is rallying support, while his untested Conservative challenger David Cameron has watched a 20-point lead dwindle to as little as two points. With neither of the two main parties on course to win an outright majority, Clegg and his Lib Dems could wake up on May 7 holding the balance of power.

Then what? A 1977 Lib-Lab pact to shore up a minority Labour government proved short-lived. The Lib Dems will only agree such a course again in return for very significant pledges. Clegg resists all speculation about possible deals. If there's a hung parliament "of course we'll work out a stable government," he says. "What people are entitled to ask is what are the things you will push for in whatever situation you find yourself?" (Read: "David Cameron: UK's Next Leader?)

It's a good question. Few Brits would disagree with Clegg's calls for greater transparency in a parliament tainted by last year's serial revelations of the ways in which some MPs and peers milked a lax expenses regimen, Lib Dems among them. He's also likely to use any leverage to push for the introduction of a proportional-voting system and a right for constituents to recall MPs who break the rules. The second of those, at least, should prove uncontroversial in a country that regards its political classes as even more venal than its bankers. But Clegg's modernizing zeal, and the language he uses, could scare the horses. "I almost sound Marxist saying this, but I really think when you have a political architecture and set of institutions which is so out of whack with how people are actually behaving and acting, that can't carry on forever," he tells TIME. A little later he confides, "I've always regarded European integration not as an inhibition of British sovereignty but an extension of it." Eek.

If such phrases shock, it's not entirely unintentional. Clegg is trying to cut through the tangle of well-meaning woolliness shrouding a party that traditionally attracts more than its share of affluent supporters in sandals and bicycle clips. In an hour-long town-hall meeting in a key Lib Dem target constituency, he uses the word fair 25 times. "If I hear him say again that a child growing up in one part of [the northern English city] Sheffield has got much better life chances than a child growing up in another part of Sheffield I think I might scream," says Jo Swinson, a Lib Dem MP. "But I realize he's doing it so that everybody else hears it too." Says Clegg: "If you are in this rowdy crowded political marketplace, you have to paint in primary colors." (Read about Britain's National Health Service.)

That palette includes "greedy bankers" and a warning that debt-ridden Britain is "like an enlarged version of Iceland." There's green too, lots of it, with ambitious proposals for investing in renewable energy and axing any expansion of nuclear power. And some might see red at Clegg's trenchant views on recalibrating Britain's relationship with the U.S. The Lib Dems opposed British participation in the Iraq war, which Clegg ascribes to "this almost unseemly knee-bending allegiance to the White House. I don't think it's good for Britain," he says. "I don't think it's good for our self-respect." (Pound Woes: Why Britain's Currency Is Falling.)

It's easy to be high-minded when you're a party leader in no danger of attaining real power. But there's every evidence that Clegg's principles run deep. That matters. The accommodations he makes if Britons return a hung parliament could have an impact well beyond Westminster. For the politician — and for Britain — this is uncharted territory.

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