Editor's note: CNN contributor William J. Bennett is the Washington Fellow of the Claremont Institute. He was U.S. secretary of education from 1985 to 1988 and was director of the Office of National Drug Control Policy under President George H.W. Bush.
(CNN) -- Joe Lieberman, Jane Harman and Jim Webb have all recently announced they will be retiring from Congress. Add to this the news that funding for the Democratic Leadership Council has dried up and it will be closing its doors, and that the self-described moderate Blue Dog coalition of House Democrats has dwindled from 54 members last year to 25 this year and we can draw a lamentable conclusion: It's the end of the moderate Democratic party.
That moderate party, once a place of giants like Presidents Harry Truman and John Kennedy, Sens. Henry "Scoop" Jackson and Daniel Patrick Moynihan, has steadily moved leftward ever since the 1970s. It had one last hurrah with the influence of the DLC on Bill Clinton in the 1990s.
Once in a while, and too rarely in my view, one could still hear echoes from that Democratic Party of yesteryear, a party of social liberalism but muscular foreign policy, and when it was heard it was usually from the microphone in front of Joe Lieberman or Jane Harman. But Joe Lieberman was defeated in his own party in Connecticut and had to run as an Independent while Jane Harman was sidelined by her party leadership in the House. Now they are all departing on their own.
The absence of their voices and politics will be missed -- but it is an open question if they will be missed more by Democrats or more by independents and Republicans. Either way, I submit, it is too bad for the country. Such an absence of conviction for centrism, of independent thinking in the Democratic Party, is not healthy for the party and, more importantly, it is not healthy for American politics.
Some have made the observation that, lately, President Barack Obama has moved (and moved staffers) toward the center, but does anyone truly believe he did so out of conviction? National Review senior editor Ramesh Ponnuru put it this way recently: "the Obama of 2013 [should he win re-election] will be closer to the Obama of 2009 than the Obama of 2011. The move to the center is tactical and temporary."
Clearly, at a national level, Democrats understand the need to speak as centrists. The resounding defeats of Jimmy Carter and then Walter Mondale, Michael Dukakis and John Kerry (candidates satisfied to run as unabashed liberals) have taught the party that much. The only Democratic victors since 1976 (when Jimmy Carter, by the way, ran as a conservative Democrat) have been the DLC's Bill Clinton and Obama.
And Obama ran not so much as a liberal or moderate but, rather, as a post-partisan, different kind of voice in the party -- unafraid to salute the likes of Ronald Reagan, even in his primary campaign.
But having mentioned Reagan, it is worth noting something he achieved that Democrats generally have not: massive cross-party appeal. There was such a thing as a "Reagan Democrat" (I was one of them), and the coalition of self-described Democrats who supported Reagan was as much a key to his success as it was a mark of it. Reagan received just under 30% of the registered Democratic party vote in 1980 and 1984. What we have not heard of is such a phenomenon on the other side (e.g., a "Clinton Republican" or an "Obama Republican").
While it is true Obama received 9% of registered Republicans' support, and a handful of moderate Republican endorsements in 2008, I very much doubt those numbers will hold for him in 2012 and the phenomenon of massive cross-party appeal will remain as unidirectionally Reagan's.
The absence on the scene of the likes of Lieberman, Harman, Webb and the DLC will only solidify this. And the moderating voice in the Democratic party will become ever more silent.
The opinions expressed in this commentary are solely those of William Bennett.