One of the reasons the Republicans are better at politics than Democrats is that they are disciplined enough to speak with a single voice even when they disagree, or are upset, or are losing. In fact, I think it's
the reason why they succeed. They don't have to tell the truth or have the facts to support them, but as long as they all say the same things and repeat them often enough, people will believe them. The Democrats would do well to take this technique to heart. We'd have the advantage of being able to use the truth for this purpose.
Republicans are always saying "liberal media". They all repeat it over and over and people have assumed it's true in spite of all the evidence to the contrary (e.g. newspapers are more likely to endorse Republicans, conservatives dominate talk radio, etc.) Republicans have made the myth so pervasive that they've pushed media outlets further and further right and even convinced some moderates and Democrats that it's true! All Democrats have to do is constantly repeat "overwhelming conservative mass media." If all Democrats are saying it, it will have an impact. Republicans are pushing one way here, and we need to push back just as hard or harder.
Republicans always talk about "tax-and-spend liberals". It's a simple meme that takes hold, even if it's not accurate. To counter it, Democrats need to point out the fiscal irrepsonsibility of the neocons. Those "steal and spend Republicans". Or those Republicans that like to tax children via deficits, etc.
We can come up with some new ones too. Like bullheaded, warmongering conseratives. Or the conservatives that hate science and hate progress. Or the baby-eating conservatives. You get the idea.