House Democrats from the nation's manufacturing heartland are vowing to fight President Obama's push for a major trade deal in the Asia Pacific, saying the pact will harm U.S. jobs and charging that the administration has not been transparent with Congress in its negotiations.

"The administration refuses to change its approach to secret negotiations and is pushing to send a final package to Congress with almost no ability for us to scrutinize it," Rep. Rosa DeLauro (D-Conn.) said Monday on a conference call with reporters. "Enough is enough: no more offshoring, no more NAFTA-style trade deals."

Rep. Tim Ryan (D-Ohio) said that unless the administration made significant changes to the proposed deal, including new protections on currency manipulation, Democrats would "fight the administration tooth and nail on this."

The opposition from Obama's own party, and a significant portion of his liberal base, has presented a conundrum for the White House as it pursues the 12-nation Trans-Pacific Partnership (TPP), which is the economic centerpiece of the administration's strategy to re-balance U.S. attention and resources to Asia. Negotiators from the 12 countries are in Washington this week for another round of talks in hopes of making progress toward an agreement in principle this coming spring.

White House advisers said they believe there could be more support for the trade pact in the new Congress because Republicans, who will take control of the Senate, are generally more supportive of free trade agreements. Last week, Obama touted the pact during an appearance with business leaders in Washington, calling on opponents not to "fight the last war" against previous trade pacts such as the North American Free Trade Agreement (NAFTA). He said those who oppose the deal are in favor of maintaining the "status quo," a remark that angered labor unions and some Democrats.

The administration has said the proposed pact, which would encompass nations representing 30 percent of the world's gross domestic product, would increase U.S. exports by lowering tariffs, while also imposing higher labor and environmental standards on other nations. But opponents said they fear that the deal will lead to more outsourcing of U.S. manufacturing and agricultural jobs.

"The notion that any of us are wedded to the status quo is false," said Rep. Dan Kildee (D-Mich.). "All of us agreed that in a period of globalization we want trade to be more free and clear. But to me the status quo is continuing to accept a paradigm that allows an agreement to be negotiated without Congress's role being considered."

With the topsy-turvy alliances in play, the first political test for Obama is expected to come early next year: The administration has vowed to work with Republicans to pass a measure that would give Obama fast-track authority to cut a deal with the other nations that could not be changed by lawmakers before a vote in Congress. Such a measure is considered crucial, administration officials say, because other nations need confidence that the U.S. will bring its best and final offer to the negotiating table.

But the Democratic Congress members said Obama administration trade negotiators have not been forthright in explaining what is in the deal, so they are opposed to granting Obama the fast-track authority. U.S. Trade Representative Michael Froman's office said he and his staff have held more than 1,500 meetings and discussions with members of both political parties since the TPP talks began in earnest several years ago.

DeLauro and other House Democrats met last week with Sen. Sherrod Brown (D-Ohio) to discuss strategy in opposing the TPP. Obama would need Democratic votes in the Senate for a bill to go forward.

"This administration has done more public dialogue and outreach on TPP than on any other trade agreement in U.S. history, including providing every member of Congress with access to the text of negotiations," USTR spokesman Matthew McAlvanah said Monday.