HANOVER, N.H. - Former Vice President Joe Biden posed a stark hypothetical to voters in New Hampshire Friday as he discussed today's volatile political climate: What if Barack Obama had been assassinated?The comment came toward the end of a town hall meeting on the campus of Dartmouth College ostensibly about healthcare issues. It was not part of Biden's standard stump speech and was rarely, if ever, heard before.Biden, as part of a meandering discussion that included mental health issues and school shootings, talked about formative moments in his college years: the assassinations of his "political heroes," Robert F. Kennedy and Martin Luther King, Jr."My senior semester, they were both shot and killed," he recalled. "Imagine what would have happened if, God forbid, if Barack Obama had been assassinated after becoming the de facto nominee. What would've happened in America?"It was a jarring point to raise on a day the Biden campaign had sought to capitalize on Biden's partnership with the former president, on the 11th anniversary of Obama announcing Biden as his choice to serve as vice president.And it came amid increasing scrutiny of Biden's occasional verbal miscues as his campaign has more forcefully pressed the case that he is the Democrat with the best chance to defeat Donald Trump next November.Only three days earlier at an event in Iowa, Biden initially misstated the decade in which Kennedy and King had been shot, initially saying in the 1970s instead of 1968.At a second event Friday Biden quickly turned instead to a stepped up attack on the president, accusing him of becoming "more and more unhinged.""He's now feeling the pressure of an economy teetering on a recession and he's not handling it very well," Biden said. "His trade war with China is blowing up in his face. I think it's only going to make him more erratic."