NY Senator Hillary Clinton is using a line from the Kerry campaign (always a great place to crib campaign strategy from). Her line, used to a crowd of Iowans, is "I want a long term relationship....I don't want to just have a one night stand with all of you."
This line is reminisent of the "Dated Dean, Married Kerry" bumper stickers in '04, suggesting that after voters had gotten over their momentary fling with the firery former VT Governor Howard Dean, they were willing to settled down with a more electable nominee, MA Senator John Kerry.
The problem with using this line is that it doesn't apply at all. Numerous writers (the New York Times' Frank Rich being one of them), have suggested that Clinton is no more "electable" than Obama, and that "Clinton-bashing is the last shared article of faith...that could yet unite the fractured and dispirited conservative electorate."
Furthermore, the momemtum is moving in the other direction i.e. toward Obama, meaning that voters, for once, are deciding to marry a candidate who satisfies both their heart and their head.