MANCHESTER, N.H.—Former House Speaker Newt Gingrich, who has complained for weeks about the barrage of negative ads aimed at his campaign, pledged Monday to turn up the heat on Mitt Romney.

At an afternoon campaign stop in Manchester, Gingrich said he’s proven that he has “broad shoulders” over the past three weeks, but acknowledged that his attempt to run a positive campaign hasn’t worked.

The lesson after Iowa, Gingrich said, is that it was a mistake to “engage in unilateral disarmament” given the volume of attacks against him. “Now we’ll see if he has broad shoulders and see whether he can stand the heat,” Gingrich said of Romney.  

Speaking to reporters, Gingrich laid into Romney’s record at Bain Capital—surely a preview of what’s to come from the Gingrich camp in the final hours before New Hampshire’s primary. It’s also the message embraced a by a Super PAC backing the former Speaker.  

Asked about the $5 million donation to a Super PAC backing Gingrich from casino mogul Sheldon Adelson and the group’s planned aerial assault on Romney’s Bain Capital background, the former Speaker wouldn’t disavow it. 

“I think if he wants to counterbalance Romney’s millionaires, I would have no objection,” Gingrich said of Adelson.  

In other words, bring on the Super PACs.