WASHINGTON, D.C. -- Traveling the country the past few months, I have encountered habitual Republican voters so entranced by Barack Obama's potential to lead the nation that they plan to vote for him in November. Once Hillary Clinton's defected supporters return to loyalty, Obama Republicans could produce a Democratic presidential landslide. But Obama's current missteps jeopardize their support and imperil his election.

These apostate Republicans never were deluded into considering him anything other than a doctrinaire liberal who wants a more intrusive government with higher taxation and tougher regulation. But they have leaned toward him as an exceptional candidate in the mold of John F. Kennedy and Ronald Reagan, a post-partisan leader and a welcome contrast to George W. Bush's failed presidency. That impression is threatened by Obama's performance the last 10 days, climaxed by Wednesday night's debate with Hillary Clinton.

Obama's new resemblance is less to Kennedy or Reagan than to leftist author Thomas Frank, whose 2004 book, "What's the Matter With Kansas?" answered the liberal conundrum: Why do ordinary Americans vote against their own economic interests to support Republicans? Frank explained that "deranged" and "lunatic" Kansans were led away by Republicans from material concerns to social issues. Obama similarly described small town Americans turning to guns and the Bible in frustration over government's failure to take care of them -- a more genteel version of Frank. That raises the question, "What's the matter with Obama?"

Almost everybody I encounter in politics is familiar with Frank's best-seller. Democrats are united in embracing his theory but are divided about its rhetoric. While sophisticated Democratic politicians regard the book as condescending to lower-income Americans who have voted for Ronald Reagan, grass-roots activists in the party consider it gospel. They tell me Obama should not back away from what got him in trouble: his declaration to a closed-door fund-raiser in San Francisco that "bitter" small-towners in Pennsylvania and elsewhere "cling to guns or religion."

Obama and his advisers know better. Though he revealed political inexperience by thinking what he said in San Francisco would stay in San Francisco, he is savvy enough to apologize profusely for "gaffes" and "errors." But he considers his blunder one of style not of substance. Actually, while seeming to be anti-gun or anti-church is self-destructive for a candidate, even raising Frank's thesis is dangerous.

The trick is for Obama to distance himself from the rhetoric while holding to the theory, as restructured in last week's debate: "Yes, (the American people) are in part frustrated and angry" by "manufactured" issues. Indeed, he said, beating "to death" this issue is "not helping that person ... trying to figure out how to pay the bills at the end of the month."

Clinton's effort to brand Obama as elitist has failed to move the polls, probably because Democratic primary voters agree with Frank. Nevertheless, Democratic pros feel that the San Francisco incident halted an Obama surge in Pennsylvania that might have won him the state and ended Clinton's campaign tomorrow. What really worries them, however, is the impact on independents and Republicans who had been entranced by the young man from Chicago. Now, they wonder whether the appealing unifier is really a divider.

Obama is trying to change the subject, but he lost his cool demeanor when ABC News questioners Charlie Gibson and George Stephanopoulos returned to his San Francisco statement (among other difficult issues) in Wednesday's debate. In watching campaign debates dating back to Kennedy-Nixon in 1960, I never before had seen a candidate criticize the moderator or challenge his premises so often (on at least eight occasions). "Look, let me finish my point here, Charlie," said Obama, after Gibson had interrupted him following a 126-word answer.

The other unprecedented element was the deluge of abuse heaped on the two ABC moderators by reporters on the media, television critics and political writers. They object to prolonging what amounts to a debate on "What's wrong with Obama?" Exploring whether Barack Obama is a modified Thomas Frank does not depend on television talking heads or Hillary Clinton. Supporters of John McCain, seeking to reel back the Obama Republicans, will press the issue from now to November.