New Mexico Governor Bill Richardson was supposed to be the cautious candidate Democrats respected but never got excited about. With his extensive diplomatic experience and his hunger for a return to the national stage–if not as a realistic candidate for the presidency then as a top vice presidential prospect or the next Secretary of State–the man who served as Bill Clinton’s Energy Secretary and United Nations ambassador was tagged at the time of his January announcement as a deliberate, capable but almost certainly inconsequential contender for the 2008 nomination. But Richardson has refused to play his assigned role, and with an unexpectedly resolute antiwar stance and a freewheeling campaign style that distinguishes him from the field’s punch-pulling frontrunners, he is the first member of the race’s “also-ran” pack to elbow his way from the margin of error to the verge of serious competition.

Richardson’s edgy, opinionated and at times risky high-wire campaign has gained him double-digit poll numbers in the first primary state, New Hampshire, where he has begun to attract endorsements from key local Democrats and favorable reviews from the state’s influential newspapers. One recent New Hampshire poll put him ahead of John Edwards. A summer survey of Democrats in the first caucus state by Iowa’s Des Moines Register had Richardson in front of Barack Obama and just five points behind Hillary Clinton as the choice of the most likely caucusgoers. In Nevada, another early caucus state, Richardson’s support has grown from 2 percent in March polling to 11 percent in August.

Why is Richardson clicking? Against a field of first-tier candidates (Clinton, Obama and John Edwards) who don’t mind savaging the Bush Administration’s management of the Iraq imbroglio but who regularly fall short of proposing clear exit strategies, Richardson offers not just a résumé but specifics–and a sense of urgency. His TV ads in the early caucus and primary states identify him as the candidate with “the only plan that pulls every single soldier out of Iraq.” As the contender with the most international experience–save, perhaps, hapless Senate Foreign Relations Committee chair Joe Biden–Richardson says it is not merely possible but necessary to end the US military presence in Iraq and to replace it with diplomacy and targeted aid initiatives. Rejecting all the dodges of the frontrunners, Richardson argues, “If we are going to get out, we need to do it now.”

For all his much-ballyhooed experience, and for all the sole Hispanic contender’s supposed–if largely unconfirmed–appeal to the party’s rapidly expanding Latino voting bloc, Richardson recognizes that it is his position on the war that is giving his candidacy traction. Of course, he’s glad to discourse on how to tackle the crisis in Darfur and his concerns about Pakistan, and he’s more than willing to detail his mainstream progressive positions on everything from gay rights to net neutrality. But the governor’s antiwar position is now the primary focus of his media buys, his savvy campaign appearances and his aggressive new direct-mail fundraising appeals to liberal donors. That’s smart politics. Richardson’s Iraq stance is at once refreshing and reassuring for grassroots Democrats, who polls suggest are increasingly frustrated with the cautious approach of party leaders. In the former UN ambassador they get a candidate who knows his way around the world, who understands the delicacy of diplomacy, who actually negotiated with Saddam Hussein and yet whose statements echo the assessment (if not quite the Department of Peace rhetoric) of antiwar absolutist Dennis Kucinich. As party leaders seek to exclude from debates two outspoken advocates for bringing the troops home, Kucinich and former Alaska Senator Mike Gravel, Richardson’s résumé and his poll numbers assure him a place on the stage and an ability to keep prodding the frontrunners to clarify their murky positions on Iraq.

None of this means Richardson is on a fast track to the nomination. He’s still playing catch-up in a brutal fundraising competition, and he remains a largely unexamined contender with his share of political baggage–the Energy Department’s bungling of the Wen Ho Lee nuclear espionage scandal during Richardson’s tenure is an embarrassing footnote, as is his post-Cabinet service on the boards of energy firms with troubling environmental records. But no 2008 Democratic candidate has come further on the basis of a bold stance on the essential issue of the race than Richardson. At the very least, he will make it difficult for Clinton, Obama and Edwards to continue dancing around the core questions of the war. And if the leading Democrats fail to make convincing moves toward withdrawal, Richardson is better positioned than any other candidate to ride that issue to the center of the competition.