The thinking typified in this post is why Democrats keep losing elections. They can't accept the facts, so they make up reasons like dirty tricks, or cheating, the complicit media, or (GASP!) a vast right-wing conspiracy. The real reason, however, is fairly simple. In the last 40 years, Democrats have won when the fielded a centrist candidate and lost when they fielded a liberal candidate.
This year, they've got another liberal candidate (although one with lots more appeal than Kerry, for example) and they're behind. So they start making excuses earlier than ever. That may make them feel better but as any troubleshooter knows, if you don't correctly identify the cause of a problem, you'll never get the fix right. So, they keep on losing election after election.
I'm sad to see this, because while in the short run it will keep Republicans in the White House, it's not good for the system. Having a large group of people disaffected because they thought they were cheated is not good for America.