Gallup is out with a poll today that tells us: “Mitt Romney is the leader for the GOP nomination among the current field of official candidates, supported by 27% of Republicans, compared with 18% for Michele Bachmann. However, Rick Perry would essentially tie Romney, with Sarah Palin and Rudy Giuliani close behind, in a scenario in which all three of these undecided candidates entered the race.” That in turn spurs stories such as “Poll: Romney weakening, GOP field still in flux.” Romney might be “weakening,” but this poll sure doesn’t prove that. Why not? There are four cautions that should apply to this and every other campaign poll.

First, early polls are largely built on name recognition, and as others become known or enter the race that advantage fades for the better known candidates (unless, like Tim Pawlety and Jon Huntsman, the electorate never shows any interest in them).

Second, the best days for a candidate are often before he enters a race. The “idea” of a Fred Thompson was exceptionally appealing to conservatives; the reality was not. That is not to say Perry will be another Thompson, but we don’t know that from a poll in July.

Third, this Gallup poll, and many like it, aren’t based on primary voters. Gallup explains its poll is based on “a random sample of 1,088 Republicans and Republican-leaning independents, aged 18 and older, living in all 50 U.S. states and the District of Columbia.” Can those independents vote in their state’s primary? Are these likely primary voters? Who knows.

And finally, we don’t have a national primary. The joke in 2008 was that Rudy Giuliani was leading everywhere there wasn’t a contested race. In other words, he wasn’t leading in a meaningful poll.

This doesn’t mean that Gallup is “biased” or a “bad poll.” It just means that the results don’t translate into the headlines many media outlets generate. This is understandable. “Romney fades” is a compelling headline. “Early poll with no predictive value shows leveling of name recognition” isn’t.

At this stage, the best indicator of the race’s direction is placement in state polls where there is an active race and fundraising (which translates to enthusiasm and sustainability). Now I’ve said that money isn’t everything in politics and that is highly overrated, but no one disputes that a candidate who raises a piddling amount is failing to build a base of support.

Polling is the honey that draws swarms of political reporters. Everyone wants to know who is “winning” now. But let me remind you that in April Donald Trump was tied with Mike Huckabee at 16 percent. Romney was at 13 percent. Enough said.