A liberal can win the Republican nomination in 2008 because the Republican base is more liberal than people think it is. Look what happened in IL this spring with that awful woman running for governor against that equally awful governor.
Your wrong and confused.
They are either more liberal than many of us that consider ourselves conservative believe, or they keep buying into the idea of nominating someone "electable".
The rather liberal press and the very liberal and well funded political groups have gotten very good at attacking conservative candidates and making commonly held beliefs sound radical.
The liberals are winning the propaganda war. The truth has little power in politics these days, and it seems fewer and fewer politicians from either or any party have much respect for the truth anymore.
However, there is still a strong conservative base in the Republican Party. It's motivating that base that is difficult, especially since much of the leadership in the state Republican parties are not conservative and see true conservative as a threat.
However, as ballot issues on traditional marriage have shown, conservative values are still a very strong factor in politics.