Republican Mitt Romney is pledging to repeal the Dodd-Frank financial regulations, a promise that is helping him reap millions from Wall Street contributors. But the presidential candidate is silent on how, without Dodd-Frank’s new rules, he would prevent the nation’s investment houses and bankers from once again engaging in the sorts of risky, poorly regulated practices that caused the 2008 financial crisis. It is a notable gap in the platform of a candidate who is running on his business acumen and who, at every turn, sharply criticizes President Obama’s handling of the post-meltdown economy. If elected president, Romney is pledging to repeal the Dodd-Frank financial regulations, but he hasn’t said how he would prevent the Wall Street practices that led to the 2008 financial crisis.