There are no perfect candidates in American politics. But during the national political career of George W. Bush, the Republican Party's electoral success has come in large part from making sure that voters perceived Democratic candidates as less perfect than their Republican opponents.
Think of Al Gore in 2000 (painted by the Republicans as a liar, an exaggerator and without principles). Or John Kerry in 2004 (cast as a flip-flopping, weak Frenchman). Or a passel of Democratic candidates for the House and Senate in 2002 and 2004, defined as tax-raising, weak-on-defense liberals.
Under the direction of political architect Karl Rove, the Republicans have taken the past statements and actions of Democrats, from the top of the ticket on down, and painted a portrait of the Democratic Party and its candidates that not only energized conservatives to turn out in record numbers but drove a lot of independents to the Republican side.
The mechanics of the GOP's message delivery -- from the words of President Bush and Vice President Dick Cheney to television and radio advertisements, e-mail messages, church fliers and more -- are more sophisticated than anything the Democrats possess.
The widespread assumption among Republicans going into the tough terrain of the 2006 midterms -- and the widespread fear among Democrats -- was that the Republicans would once again define their opponents in terms that would turn voters off.
This approach -- "disqualifying" the Democratic candidates as "unacceptable" -- was considered vital because of the tough political climate facing the president's party in his sixth year in office, made worse by the war in Iraq, high gas prices and ethics scandals.
Many Republicans believed that what worked on Kerry in 2004 would work on the far less-experienced Democratic candidates running in competitive races all over the country.
Republicans would turn a potential evaluation of their incumbent candidates -- a referendum in troubled times -- into a "choice" election, in which the Democratic choice would appear to many as too liberal and too kooky.
But with just over two weeks to go before Election Day, so far, public and private polling, as well as interviews with campaign strategists in both parties, suggests that these standard Republican tactics are not working.
In Ohio, for instance, where the Democrats are running extremely liberal House members for both governor and the U.S. Senate, their candidates are far ahead in the polls, despite increasingly urgent attempts to paint them as out of step with the Buckeye State. In most of the races targeted by both sides, Democrats' poll standing holds steady, or is even improving.
Republicans cannot make the war in Iraq stop before Election Day or wipe away the stain of the various ethics controversies or make Americans suddenly feel better about the economy. They've believed for most of 2006, however, that they could still hold on to power by making the prospect of Democratic rule seem worse.
Why the Republicans' negative attacks have not worked as they have in the past is a topic for another day, but for now, their failure is one main reason the president's party appears headed for a less-than-perfect day on Nov. 7.
Mark Halperin, the political director of ABC News, is co-author of "The Way to Win: Taking the White House in 2008" with John F. Harris of The Washington Post. Go to thewaytowin2008.com to find out more.