First, Gallup polls over the past 60 years show that no president with an approval rating under 47 percent has won reelection, and no president with an approval rating above 51 percent has lost reelection. (George W. Bush's approval rating in the weeks before the 2004 election hovered around 50 percent.)
The 2012 election will be primarily about our current president and whether voters are satisfied with the country's direction.
From the above, the article's central conclusion:
Who the Republican candidate is, and his or her qualifications and abilities, will matter only if Obama's approval rating is between 47 and 51 percent going into the fall of 2012. Interestingly, in the latest Gallup poll Obama's approval rating was at a precarious 49 percent.
This misses two points, one obvious, the other subtle. The obvious point is simply that the past is no guarantee of the future. The subtle point is that Presidential approval ratings may cause certain types of candidates to come to the fore. Take Barry Goldwater and Lyndon Johnson in 1964. Before the election, Johnson's approval ratings were around 74%. They were similar while Goldwater won the republican nomination in the face of competition from William Scranton and Nelson Rockefeller, both moderate "Rockefeller" republicans (Nelson was the namesake). In the face of a widely popular President, the party chose a firebrand. In the face of an unpopular George H. W. Bush, whose approval rating was 41% by the time Bill Clinton cleaned up on Super Tuesday in 1992, democrats nominated a New Democrat to office--had Jerry Brown been nominated, it's by no means clear that even a 41% approval rating would have caused a Republican loss .
The lesson that matches with intuition might be: given you are challenging an incumbent, when a race is hopeless, pick candidates who appeal to your base. When a race is winnable, pick moderate candidates who have a chance.
To be sure, one can object to this specific conclusion as much as the Washington Post's. Nonetheless, the point remains that the qualities of the candidate of choice vary with Presidential approval ratings and are not exogeneous to them. The author's suggestion that a party can "break" with tradition and choose a firebrand is ludicrous--the prediction is outside his implicit model.