During any primary season, there's a balancing act between ideological lines of attack that only hurt opponents during a primary, and the types of broader character attacks that could carry over to the general election. For instance, in 2012, attacks on Mitt Romney for not being a true conservative were less damaging to him in the long run than, say, Newt Gingrich's attacking him for laying off people during his business career. The increasingly nasty fight between Hillary Clinton and Sen. Bernie Sanders is now entering the state where Sanders is starting to say things that Republicans could use against Clinton in the general election.
At a rally Wednesday night, Sanders — responding to Clinton comments questioning his readiness to be president — went on an extended rant questioning her qualifications. "Let me just say in response to Secretary Clinton: I don't believe that she is qualified if she is, through her super PAC, taking tens of millions of dollars in special interest funds. I don't think you are qualified if you get $15 million from Wall Street through your super PAC."
This is the type of clip that could be deployed against Clinton by either likely Republican nominee. Sen. Ted Cruz and Donald Trump are both running as outsiders, and Trump explicitly has based a big part of his populist campaign pitch around the idea that because of his wealth, he isn't beholden to Wall Street and special interests.
This is a departure from Sanders from declaring during a debate last year that he was "sick and tired" of hearing about Clinton's "damn emails." Liberal Greg Sargent writes that Democrats are likely to unify after the race is over, which I'd assume is true.
But at the same time, clips such as the one from Sanders last night could enable Republicans to cut an ad along the lines of the famous Ted Kennedy "No more Jimmy Carter" ad in 1980 in which Ronald Reagan deployed a anti-Carter rant from that year's Democratic primary to great effect.