Don't get out

I don't think any of the Republican Presidential candidates should get out of the race. Each candidate should be expressing their beliefs as much as possible.
They are many states where Santorum could win. Texas, Mississippi, and Alabama but even if Gingrich drops out, it will be difficult for him to get the nomination.
Don't let one person have a Monopoly on the ideas being discussed. By having the future nominee fight for the nomination, it will allow the people to help shape the views of the nominee. The nominee will need the support of everyone who supported them during the race to gain delegates. Each candidate needs to be able to expand their ideas to incorporate the idea of others. It is not enough for the person to expect the people to simply support his ideas, it is important for the nominee to support the ideas of the people.

Too many times in Presidential elections, the candidate presents their beliefs and the people have to pick the lesser of two evils. This needs to be the time the nominee listens to the people and begins articulate what people are feeling, and thinking.
Romney has difficults doing this. Saying that he knows some NASCAR team owners does not help him relate. If he is given the nomination by the others dropping out, he won't mold his ideas into the shape needed.
Santorum calling President Obama a snob does not help. Since he missrepresented the Presidentes words, it makes him look foolish.
Fighting for the Nomination will make the nominee stronger. Extended fights only hurt if it results in the nominee not being able to have money to run.