Updated

High unemployment, anemic growth, defections in key groups such as independents and Hispanics, and unpopular policies are among the reasons President Obama is unlikely to win re-election. But likely to lose is far from certain to lose. If Republicans make enough unforced errors, Mr. Obama could win.

The first such mistake would be forgetting that the target voters are those ready to swing away from Mr. Obama (independents, Hispanics, college educated and young voters) and those whose opposition to Mr. Obama has deepened since 2008 (seniors and working-class voters).

These voters gave the GOP a big win in the 2010 midterm. They are deeply concerned about the economy, jobs, spending, deficits and health care. Many still like Mr. Obama personally but disapprove of his handling of the issues. They are not GOP primary voters, but they are watching the contest. The Republican Party will find it more difficult to gain their support if its nominee adopts a tone that's harshly negative and personally anti-Obama.

The GOP nominee should fiercely challenge Mr. Obama's policies, actions and leadership using the president's own words, but should stay away from questioning his motives, patriotism or character. He will do this to his GOP opponent to try to draw Republicans into the mud pit. They should avoid it.

Karl Rove is a former senior adviser and deputy chief of staff to President George W. Bush. He is a Fox News contributor and author of "Courage and Consequence" (Threshold Editions, 2010). To continue reading his column in The Wall Street Journal, click here.