But political experts have doubts. They point to the unusual circumstances that shaped the race: It was the first wide-open primary since 1995, with a truncated campaign season of just three months. It was an off-cycle contest that drew only 14 percent voter turnout. And Chicago — where all the top city leaders are already advocates of an assault-weapons ban — has seen a spike in street violence. More than 40 people were killed in Chicago last month, the deadliest January in a decade.
"He pummeled the race in one direction, and (most) of the people didn't participate," said Thom Serafin, a longtime Chicago political consultant. "If they're going to take that model around the country, good luck."
Bloomberg's foray into congressional contests has been inconsistent so far.
He formed his super PAC weeks before the November election and has spent more than $12 million to back roughly half a dozen candidates nationwide. Guns weren't an issue in all of the races, and when they were, he didn't always support the strongest anti-gun advocate.
In another Chicago-area district, he backed Republican incumbent Rep. Bob Dold over newcomer Democrat Brad Schneider, even when Schneider had a stronger anti-gun stance. Dold lost.
Bloomberg has also supported candidates outside of major urban centers. He backed newly elected Rep. Gloria Negrete McLeod, a California Democrat who ousted an incumbent, in a district east of Los Angeles that's a mix of industrial and farming communities hit hard by the economic downturn.
The NRA said Kelly's victory doesn't prove anything about Bloomberg's influence, particularly since the gun-rights group didn't spend anything on the race. A better example, the group said, would be last year's campaign in central Florida, where NRA-backed Rep. Dan Webster defeated a Democratic challenger backed by Bloomberg.