Washington ? It almost defies common sense to suggest that Howard Dean will leave a lasting and positive legacy for the Democratic Party. Nonetheless, that is my strong hunch.

Dean is easy to dismiss. After all, the former governor of Vermont is a man who led all the polls for months before the start of this campaign year, yet blew his advantage so quickly and so thoroughly that he did not win a single primary or caucus. His constituency consistently was tilted toward the young, very liberal, highly educated and angriest of anti-Bush voters.

That does not describe a large or vital bloc even within the Democratic coalition, so it is doubtful that Dean supporters will play a crucial role in deciding whether John Kerry or John Edwards becomes the party’s nominee. Now that Dean has ended his active campaign, his endorsement probably is of minimal value.

Even acknowledging all of that, it will not surprise me a bit if the Dean campaign turns out to be a significant milestone in Democratic history. Losing efforts often produce long-term gains for the party of the failed candidate, if the campaign becomes a cause for those who supported it. And so it is likely to be with Dean. His run for the White House, which ended last week, may mean little in the politics of 2004 — but a great deal more in years to come.

That prediction is not as much of a gamble as it may seem, because we have seen this pattern before. Candidates who attract a passionate following — because of the issues they raise, rather than their own White House credentials — frequently launch their acolytes into political careers that become the next generation’s richest source of leadership.

Think of Barry Goldwater on the Republican side or George McGovern and Eugene McCarthy for the Democrats, and you can understand that, though they were seen as losers at the time, the energy they created in their campaigns fueled dozens of valuable legatees.

Ronald Reagan cut his political teeth in the Goldwater campaign; Bill Clinton tested his skills for McGovern. Others who found their inspiration at the same time moved into Congress, state government and the party structure.

It is true that Goldwater and McGovern were far more successful than Dean — they both won nominations — and McCarthy helped drive an incumbent president out of office in 1968. But Dean is like them in one vital respect. Though voters decided he did not have the personal qualities they seek in a president, his definition of the policy choices facing the country resonated so strongly that it changed the entire political environment.

Until he made the war in Iraq the focus of his race, the decision to go after Saddam Hussein was not broadly questioned in this country. Democrats were ambivalent on the subject, and Republicans were solidly behind the president.

It was only after Dean spoke out that other Democrats, including Kerry and Edwards, found their voices and began challenging the assumptions that drove Bush’s decision and the steps he took to manage the war and its aftermath.

Dean was also the boldest critic of the central piece of Bush’s domestic policy — the massive reduction in federal income tax rates, especially for the top brackets. Almost single-handedly at first, he put those two topics on the agenda for the 2004 election, and they will remain there — though he is gone.

That does not, of course, guarantee that his views will prevail. It took years for Goldwater, McGovern and McCarthy to see public opinion finally shift in the direction they had been advocating.

But the pattern-breakers’ followers find continuing motivation in the ongoing struggle, and so it will be, I believe, for the Dean people. Many who rallied to his cause will remain active in politics; you can see it happening in Iowa and New Hampshire.

The Democratic Party and ultimately the country will be the beneficiaries of the shot-in-the-arm the Vermont doctor administered to and through his followers. Just wait and you will see.

– David Broder is a columnist with the Washington Post Writers Group.