President Barack Obama fired back at members of his own party who accuse him of supporting a massive trade deal that champions corporate interests and lobbyist groups.

During a speech on Thursday, the president defended his support of the Trans-Pacific Partnership (TPP), a global trade deal currently being negotiated between the U.S. and 11 Latin American and Asian countries.

Proponents of the TPP deal, which has been in the works for years, say it will expand trade and investment for the U.S. while providing a boost to U.S. exports and small businesses. It will also serve to provide a forum for promulgating labor standards and resolving disputes, reports CBS News.

However, trade unions, environmental groups and high-profile Democrats like Sen. Elizabeth Warren say that TPP would send American jobs overseas. According to critics, it would also put American workers in direct competition with low-paid workers overseas.

Opponents also note that the White House and Republican-controlled Congress are pushing to "fast-track" the secret trade deal in order to limit public debate and influence from lawmakers.

On the other hand, supporters say that the deal needs to to be kept secret during the negotiating process for strategic reasons. Meanwhile, adversaries point out that leaked drafts suggest that the deal leans in favor of big corporations and special interests groups.

Nevertheless, Obama fought back at his critics on the Left, arguing that the trade deal would benefit middle class Americans.

"When people say that this trade deal is bad for working families, they don't know what they're talking about," Obama said at an Organizing for Action rally on Thursday, reports Reuters. "I take that personally. My entire presidency has been about helping working families. The Chamber of Commerce didn't elect me twice -- working folks did.

"I spent a lot of time and a lot of political capital to save the auto industry. Why would I pass a deal that would be bad for U.S. auto workers?"

Although the Republican-controlled Senate could vote on the fast-track legislation next week, it is likely that the trade deal will opposition in the House from the majority of Democrats who are refusing to sign it.