They call on a brain researcher:

when Sen. John F. Kerry of Massachusetts let a Swift-boat veterans group drag his reputation through the mud (2004), when Al Gore put a nation to sleep with his talk of lockboxes and Medicare actuaries (2000), and when Michael S. Dukakis said he didn’t believe in the death penalty even in the event of his wife’s rape and murder (1988), Democrats were exhibiting their single worst tendency: intellectual dispassion.
That style is ballot-box poison, said Westen. “The political brain is an emotional brain,” he said. “It prefers conclusions that are emotionally satisfying rather than conclusions that match the data.”
When Westen and his Emory colleagues conducted brain scans during the 2004 presidential campaign, they found that partisans of either side, when presented with contradictory statements by their preferred candidates, would struggle for some seconds with feelings of discomfort, then resolve the matter in their candidates’ favor.
The scans showed that to do this, they used the part of their brain that controls emotion and conflict. The area that controls reasoning was inactive — “the dead zone,” Westen said.
Westen writes that it doesn’t make sense to argue an issue using facts and figures and to count on voters — particularly the swing voters who decide national elections — to make choices based on sophisticated understandings of policy differences or procedures. He says Democratic candidates must learn to do what Republicans have understood for many years — they must appeal to emotions. And (talking to you, Mr. Gore) stay away from numbing statistics.