With New Hampshire's crucial day of decision here, Web sentiment Monday soured on most of the Republican field as the second-tier contenders shifted into increasingly negative campaign modes, taking shots at each other and Mitt Romney. The accumulated buckshot sent Romney's “favorability rating” plunging 34 points from Monday’s tally. That showing may test Romney’s hope of quickly sewing up the nomination—and suggests the GOP frontrunner may still be in for a long slog through the South Carolina mud next week.

The only candidate who rose much above the fray was Jon Huntsman, who’s staked his presidential hopes on a strong finish in the Granite State. Huntsman’s favorability Monday was a field-leading 54, up 7 points from Sunday,

The Oracle tracks 40,000 news sites, blogs, message boards, Twitter feeds, and other social-media sources to analyze what millions of people are saying about the candidates and hot-button issues each day. (See methodology here.)Huntsman has been trying to capitalize on his new momentum as Google search results for his name doubled from Saturday to Monday by buying an ad for searches of his name that shows the word “surging” and links to his campaign site. (Hat Tip: Morning Score.)With Newt Gingrich dedicating himself to assaulting Romney, both men saw their favorability numbers plunge into negative territory on Monday.