Ann Seltzer's polling for the Des Moines Register/Bloomberg Politics has long been the gold standard for Iowa polling, and this is hot off the virtual presses:
Clinton 37
Sanders 30
Biden 14
O'Malley 3
Without Biden:
Clinton 43
Sanders 35
In late May, Clinton led Sanders in this poll, 57-16, with 8 for Biden.
What's more?
"This feels like 2008 all over again," said J. Ann Selzer, pollster for the Iowa Poll.
In that race, Clinton led John Edwards by 6 percentage points and Barack Obama by 7 points in an early October Iowa Poll. But Obama, buoyed by younger voters and first-time caucusgoers, surged ahead by late November.
3:51 PM PT: Full methodology, xtabs, favorables and the rest online (PDF)