As the Republican primary candidates go for broke, they’re increasingly dependent on super-PAC help. Expenditure reports filed yesterday reveal that Mitt Romney’s campaign spent almost $19 million in January, three times more than he raised. Gingrich spent close to $6 million, while raising only $5.6 million. But the super PAC supporting Romney spent close to $14 million the same month, mostly attacking Gingrich, while Gingrich spent almost $11 million returning fire. Overall the super PACs supporting the four main GOP candidates raised $22.1 million in January and finished the month with $19.4 million in the bank, $5 million more than the candidates had. The influx of super-PAC money may be responsible for the increase in negative ads. Four years ago, just 6 percent of campaign ads in the GOP primaries attacked other Republicans. This year, more than 50 percent do so. Seventy-two percent of PAC ads are negative.