Editor's note: David Frum writes a weekly column for CNN.com. A special assistant to President George W. Bush from 2001 to 2002, he is the author of six books, including "Comeback: Conservatism That Can Win Again," and is the editor of FrumForum.
(CNN) -- The exit of former Arkansas Gov. Mike Huckabee from the 2012 presidential race opens a huge void in the Republican field.
Who now will speak to the concerns of middle-class American families?
There were many flaws in Huckabee's 2008 candidacy. His cultural message was too reactionary. His so-called Fair Tax was an ill-considered gimmick. His foreign policy background was too thin.
But of all the candidates in that year of economic crisis, Huckabee was unequaled in showing understanding and regard for those families getting by on incomes of five figures and not six, seven, eight or nine.
Now in 2011, the Republican candidates have wandered even further from middle-class concerns.
You hear more from this field about imaginary threats to the Constitution than about real threats to middle-class wages. More about the gold standard than about educational standards. More about eliminating Planned Parenthood than about improving health care coverage.
Meanwhile the American middle class faces its harshest challenge since the Great Depression.
From 2000 to 2007 -- before the onset of the recession -- the median wage actually declined and the average family's debt burden grew heavier.
Then came the economic crisis: 8 million jobs lost in half a year. Housing values collapsed. Savings disappeared.
While the unemployment numbers have improved a little recently, a cohort of young Americans risk losing half a decade of their lives to chronic under-employment -- even as workers 55 and older face prematurely and permanently reduced incomes.
And even as jobs return, it's not clear that incomes will recover.
There's accumulating evidence that upward mobility has broken down in this society. Poorer Americans find it harder to escape poverty than they did a generation ago. More bitter still, there is evidence that people born poor in America find it harder to escape poverty than do people born poor in many European societies, including those supposed backwaters of socialist stagnation, Germany and France.
The Democratic Party responds to those social challenges by offering more government, more regulation and more taxes. These are not Republican answers, obviously.
But what are the Republican answers? And who will offer them?
If Huckabee will not be that candidate, then who will?
The opinions expressed in this commentary are solely those of David Frum.