John Kerry ran as a populist, and it got him nowhere in rural areas. In fact, it actually hurt him by alienating suburbanites. The best possible Democratic strategy would be to move in a libertarian direction.
Populism implies social conservatism or at least social moderatism-- and Kerry's support of gay civil unions, gun control, and partial birth abortion couldn't have helped in the suburbs. Kerry ran as a pure liberal, and if the Democrats ever nominate a pure liberal again, their results will get lower and lower. The liberal had more votes in 2000; in 2004 the result was considerably different.