What Are Endorsements Worth?

What are all the endorsements we see presidential hopefuls like Mitt Romney lining up week in and week out really worth? The Washington Post's Chris Cillizza says most are not worth much, but there are a few that can help move mountains:

"For the most part, these endorsements are aimed at building momentum but have zero practical effect on the hunt for votes. Not all endorsements are created equal, however. Some really do matter. Here's a look at six of the most important."

Three of the six endorsements Cillizza highlights are Republicans:

1. Former governor Jeb Bush (Fla.): Not only is Florida expected to move its primary all the way up to Feb. 5, 2008, it is also a treasure trove of campaign contributions if you run in the right circles. Bush knows all the political and financial road maps. He also happens to be the president's brother.
2. Rep. Steve King (Iowa): King represents the vast -- and overwhelmingly Republican -- 5th District in western Iowa. He's also one of the state's leading conservatives and an outspoken opponent of immigration reform.
3. Gov. Mark Sanford (S.C.): Most of the statewide elected officials in the Palmetto State have chosen sides, but not Sanford. Although he backed Sen. John McCain (R-Ariz.) in 2000, Sanford has made clear that he hasn't decided where to throw his support this time.

Romney's primary chances in key caucuses in Florida, Iowa, and South Carolina could rest on securing the endorsement of these three individuals. One would think Sanford leans toward McCain. Where Jeb Bush stands is not entirely clear, but I would be shocked to see Steve King endorsing McCain, which leaves the door wide open for Romney.