WASHINGTON, D.C. -- What is an "Obamacon?" The phrase surfaced in January to describe British Conservatives entranced by Barack Obama. On March 13, the American Spectator broadened the term to cover all "conservative supporters" of the Democratic presidential candidate. Their ranks, though growing, feature few famous people. But looming on the horizon are two big potential Obamacons: Colin Powell and Chuck Hagel.

Neither Powell, first-term secretary of state for George W. Bush, nor Hagel, retiring after two terms as U.S. senator from Nebraska, has endorsed Obama. Hagel probably never will. Powell likely will enter Obama's camp at a time of his own choosing. The best bet is that neither of the two 2000 and 2004 supporters of President Bush will back John McCain in 2008.

Powell, Hagel and lesser-known Obamacons harbor no animosity toward McCain. Nor do they show much affection for the rigidly liberal Obama. The Obamacon syndrome is based on hostility to Bush and his administration, and revulsion over today's Republican Party. The danger for McCain is that desire for a therapeutic electoral bloodbath can get out of control.

That danger was highlighted in a June New Republic article on "the rise of the Obamacons" by supply-side economist and author Bruce Bartlett, a middle-level official in the Reagan and George H.W. Bush administrations. He expressed "disgust with a Republican Party that still does not see how badly George W. Bush has misgoverned this country" -- echoing his scathing 2006 book, "Impostor: How George W. Bush Bankrupted America and Betrayed the Reagan Legacy." While Bartlett says, "I'm not ready to join the other side," his anti-Bush furor characterizes the Obamacons.

The prototypical Obamacon may be Larry Hunter, familiar inside the Washington Beltway as an ardent supply-sider. When it became known recently that Hunter supports Obama, fellow conservatives were stunned. Hunter was fired as U.S. Chamber of Commerce chief economist in 1993 when he would not swallow Clinton administration policy, and later joined Jack Kemp at Empower America (ghostwriting Kemp's column). Explaining his support for the uncompromising liberal Obama, Hunter blogged on June 6: "The Republican Party is a dead rotting carcass with a few decrepit old leaders stumbling around like zombies in a horror version of Weekend With Bernie, handcuffed to a corpse."

While he never would use such language, Colin Powell is said by friends to share Hunter's analysis of the GOP. His tenuous 13-year relationship with the Republican Party, following his retirement from the Army, has ended. The national security adviser for Ronald Reagan left the present administration bitter about being ushered out of the State Department a year earlier than he wanted. As an African-American, friends say, Powell is sensitive to racial attacks on Obama and especially on his wife Michelle. While McCain strategists shrug off defections from Bruce Bartlett and Larry Hunter, they wince in anticipating headlines generated by Powell's expected endorsement of Obama.

While Powell may not be a legitimate Obamacon because he never was much of a conservative, that cannot be said for his close Senate friend Hagel. He has built a solidly conservative record as a senator, but mutual friends see no difference between him and the general on Iraq, Dick Cheney, Don Rumsfeld, George W. Bush and the Republican Party. In a speech today (Thursday) at the Brookings Institution, Hagel was expected to urge both Obama and McCain to reach out to each other. At the least, Hagel is not ready to strap on armor for his longtime political ally and office neighbor, John McCain.

Published reports listing additional Obamacons do not add up to tides of conservative Republicans leaving their party. Former Federal Reserve Chairman Paul Volcker is a Democrat who entered government in the Kennedy administration. Conservative commentator Armstrong Williams (an African-American) leads me to believe that he has no intention of endorsing Obama. Conservative author Richard J. Whalen is for Obama because he sees a dead Republican Party, but he also was for John Kerry in 2004.

Nevertheless, Obamacons -- little and big -- are reason for concern by McCain. It also should cause soul-searching at the Bush White House to ponder who made the Republican Party so difficult a place for Republicans to stay.