A 9% lead with 87% reporting is a pretty large number of votes. His staff would have also have had the precinct by precinct breakdown, so if there was a significant amount of vote fraud in a particular precinct it would have been noticable, and the Huckabee campaign likely had observers in most of the precincts that they could contact for more information. Checking that the counting was still continuing couldn't have taken more than a quick phone call if his staff is remotely organized.
If the precincts were reporting one number and those numbers were getting modified when passed on, it would get noticed by the people working the precinct.
I'm not saying that vote fraud can't happen, but it is really hard to do on a wide scale, and pretty easy to detect if done on a wide scale. If they were falsifying the vote by as many votes as he was losing by, there would be a lot of evidence of it, and all he needed to do was take just a little time to look for it. I find it hard to believe that his staff wasn't already looking for the possibility of it.
So him just shooting off his mouth like he did shows that he's either an idiot that has no business running for President, or he's playing the dishonest populist political play of alleging corruption when there isn't evidence of it just to gather support and sympathy from the conspiracy theory types.
Sorry, Washington State is right up there with the top level election cheats thanks to the way the Grigoire votes were dealt with, so 9% ain't nothin' (ya dig!?)