Side by side at 26 Wall St., across from the New York Stock Exchange, freshman congressman McMahon told House Financial Services Committee Chairman Frank he was worried that Obama’s derivatives plan, released in August, would penalize a wide swath of U.S. corporations and could push jobs in his home district overseas, McMahon said in an interview.

“It’s not just the farmers, and it’s not just the Wall Street guys,” said McMahon, a member of the New Democrat Coalition, a group of 68 self-described pro-growth Democrats in the U.S. House of Representatives. “It’s across the nation. American industry uses these products for a very useful purpose, which keeps down prices and makes consumer products cheaper.”

“He said we’d be working together on this,” said McMahon, who represents a large constituency of Wall Street workers on Staten Island and in southwest Brooklyn. “We never had a philosophical difference.”

It’s not just end-users who won concessions from McMahon and Frank.JPMorgan Chase & Co.,Goldman Sachs Group Inc. and Credit Suisse Group AG lobbied McMahon and fellow New Democrat Coalition member Representative Melissa Bean of Illinois, among others, to expand the ways the legislation allows dealers and major investors to trade the contracts, according to people familiar with the matter.