In the article, The Fake Election: 10 Arguments the Republicans Aren't Making, Matt Stoller contends that the GOP isn't really trying to win the presidency. I certainly don't disagree with the premise. In fact, I don't think the Republicans have been all that interested in winning the last two presidential races.
In John McCain and Mitt Romney, you have two of the most uncharismatic and uninspiring candidates that could be imagined. In '08 as well as this year, many conservatives were/are not enthused in the least with their party's choice and seem to be going through the motions. To make matters worse, both McCain and Romney showed a prevalence for inserting their feet in their mouths which dampens any kind of conceivable momentum that can be built up.
The Democrats have gone by the same playbook before. In the 80s, they nominated two uncharismatic candidates: Walter Mondale and Michael Dukakis. Watching either give a stump speech was about as exciting as watching paint dry!
Charisma is very important when it comes to presidential politics (as well as other varieties). In order to motivate the masses to get out to work for your campaign, you must inspire great enthusiasm for your vision. Where charisma is lacking, your chances of winning are much less. And those chances are truly not good if the opposing candidate has what you lack.
Love him or hate him, Barack Obama oozes charisma. On camera, he comes off as very intelligent and caring. The man knows how to play to the sentiments of a crowd.
If defeating Obama in November was your goal, Mitt Romney (or ANY of the Republicans contenders this year) would not even have made your top ten. None of them engenders mass appeal. None of them (with the possible exception of Ron Paul) can even spell the word, charisma, let alone live it!