Jon Chait has, I think, the best explanation I've yet seen as to what's fueling the Hillary backlash. It fully merits a nice long excerpt:
It appears the grand Clinton strategy is backfiring. As a prospective national candidate, she has two great vulnerabilities. First, many voters think she's too liberal. Second, many voters also see her as cold, calculating, and unlikable.
Her response to this was to position herself in the center, cozying up with her former GOP tormenters in the Senate, staking out hawkish positions, and making an overture to cultural conservatives. The theory was that her centrist positions would endear her to moderates but that it wouldn't cost her on the left, because years of conservative vilification caused liberals to bond with her emotionally.
But instead of moderates focusing on her positions while liberals focus on her persona, the opposite seems to be happening. Moderates fear she remains too culturally divisive to win. And liberals can't stand her centrist positioning. It's the worst of all worlds. [...]
Mark Schmitt, an extremely smart liberal at the New America Foundation, coined a saying that captures the dynamic: "It's not what you say about the issues, it's what the issues say about you."
In other words, the literal popularity of an issue often matters less than the way that issue fits into a narrative of a politician's character. John McCain used his support for campaign finance reform to craft a narrative of himself as a brave truth-teller unafraid of special interests. George W. Bush in 2000 used a couple of issue positions relatively minuscule in scale (faith-based initiatives, education reform) to craft an image as a compassionate innovator.
Clinton's problem is that everything she does to staunch her perceived ideology problem compounds her perceived character problem. What she says about the issues may be popular, but what the issues say about her is that she's a shameless self-reinventor.
Gore is winning plaudits because he's in the opposite position. A couple of years ago he appeared to be veering too far left when he denounced the Iraq war and the administration's disregard for civil liberties. But now, almost no one can argue with those positions--certainly not any prospective Democratic voter. And his focus on global warming, which may not rank high on the list of voter concerns in Ohio, points to his genuine conviction on the issue. Gore cared about the environment before it was cool (or, as it were, warm.) The issue helps him more as a character issue than a substance one.
Right on. This is the same misunderstanding that doomed Kerry in 2004. It wasn't that his muddled Iraq proposals were necessarily bad policy, but that they hinted at an tendency towards vacillation which didn't jibe with what Americans wanted in their president. Presently, it's not that Hillary is so bad on global warming, or that Gore is so good on trade. It's that Clinton has anointed herself the party's putative leader but refused to lead, creating a juggernaut the left wants to fight without amassing a record they can defend. Meanwhile, Gore has emerged from exile and exhibited an array of leadership qualities without any apparent interest in the 2008 campaign. In comparison, Hillary has begun looking curiously hollow.