The Democratic primary season that ends June 3 will have seen rousing highs and distressing lows. From the beginning, we have cheered the grassroots spirit that pushed the candidates in a more progressive direction on issues like the war, the economy and the environment. We’ve hailed record-breaking voter registration and turnout. Throughout it all, we’ve supported Hillary Clinton’s right to stay in the race until the last poll closes, because we believe all voters should be participants, not spectators, in the electoral process; and we hope their mobilization will translate into lasting gains for a budding progressive majority.

But we have also warned of the dangers of the Clinton campaign’s slouch along the low road. This tendency was on full display in late May, when Clinton insensitively invoked Robert Kennedy’s June 1968 assassination as a rationale for her continued candidacy in the face of a delegate deficit that cannot be surmounted–at least by voting. Her comparison of the fraudulent elections in Zimbabwe to the dispute over the seating of Michigan’s and Florida’s delegations is outlandish and reveals a campaign fixated on its future instead of the issues. That is why we urge the superdelegates to make their decision expeditiously on June 4 so that Americans can refocus on what is at stake in this defining election.

The general election campaign will find the Republicans in delicious disarray, hamstrung by their commitment to a disastrous war and to unfettered capitalism as well as by their incompetence, corruption and cronyism. And yet, even with such fertile terrain for progressives, there are limits to the discussion as it is refracted through a presidential campaign. We have endorsed Barack Obama and are cautiously encouraged by his promise to end the war and to re-engage the world through diplomacy and fair trade; we applaud his embrace of more populist themes that highlight the need for universal healthcare and the perils of growing income inequality. (Meanwhile, John McCain equates diplomacy with appeasement and proposes more tax breaks for the superrich.) But our endorsement of Obama is not a blank check. Electing him is a crucial first step toward repairing the vast damage Republicans have wrought. Progressives should use this moment to drive issues into the campaign that have been missing from the conversation.

Where is the challenge to the bloated military budget, which equals the total amount spent by the rest of the industrialized world? Who’s talking about an exit from the “war on terror,” which has made us less secure while curtailing our civil liberties? Where is the massive public investment to repair our collapsing bridges, breached levees and bursting schools? Democrats have called for a repeal of Bush’s tax cuts for the wealthiest, but where are the proposals for a truly progressive tax system? Where is the challenge to corporate power and a serious strategy to empower workers to win their share of profits? Where are the comprehensive plans to deal with our deepening financial crisis and the tragedy of massive home foreclosures? Who’s talking about our failed “war on drugs” and our faltering criminal justice system? And while there is growing demand that we leave Iraq, who’s challenging Obama’s plan to keep troops and bases there beyond 2009?

If the limits of the debate aren’t pushed by the nascent progressive movement, we could miss a critical opening. Of course, progressives can’t lose sight of the practicalities of registering voters and getting them to the polls. But this mobilization can also push the Democratic Party to think more boldly and dissent more creatively from the failed conservative consensus of the last quarter-century.