WASHINGTON » President Barack Obama is facing opposition from fellow Democrats to one of his top priorities: winning the power to negotiate international trade agreements and speed them through Congress.

As Obama’s team works privately to line up support for the so-called trade promotion authority, a coalition of Democratic lawmakers and activists from organized labor, environmental, religious and civil rights groups is stepping up efforts to stop him.

"Fast track would be yet another insult to the American worker," Rep. Rosa DeLauro, D-Conn., said at a Thursday news conference on Capitol Hill, where she predicted the effort’s defeat. "It will not happen. We are not going to do it."

Winning the authority would allow Obama to finish and gain swift approval of the Trans-Pacific Partnership, a sprawling pact that his administration has been painstakingly negotiating.

But DeLauro and other Democratic lawmakers argue that the president is asking for carte blanche to secretly negotiate a trade deal that would cost American jobs, weaken food safety and financial regulations and undermine environmental and labor standards.

The dispute pits Obama against his own party over what the president has identified as one of the few patches of common ground between him and Republicans that could yield an accomplishment during his final two years in office. Its outcome could determine the fate of the Trans-Pacific Partnership, a complicated 12-nation agreement that would encompass 40 percent of the world economy and is a crucial element of Obama’s pivot to Asia. It is also animating an intraparty policy fight among Democrats that could shape the 2016 presidential campaign.

Obama has dispatched top officials, led by his chief envoy, Michael B. Froman, to Congress to quietly make the case for the agreement and build support for winning the trade authority.

"The president has directed us to be responsive to the very important questions that are being asked by members of Congress," said Thomas E. Perez, the labor secretary. "What’s going on now, I think, is part of the healthy give-and-take that should take place when we’re contemplating an important piece of legislation."

At the same time, Obama’s advisers see a ripe opportunity to win approval of his trade agenda given that Congress is fully under the control of Republicans who back trade liberalization.

Obama has acknowledged the challenge from his own ranks, saying last month that he must do more to explain how the Trans-Pacific Partnership would help American workers.

Lori Wallach, the director of Public Citizen’s Global Trade Watch, said presidential efforts to secure the trade power had met with hostility from Congress since the adoption of the 1994 North American Free Trade Agreement and the creation of the World Trade Organization. Those are the product of a collaboration of another Republican Congress and a Democratic president, Bill Clinton.

Those measures "woke up Congress about what ‘fast track’ means," she said, and ever since "it’s really hard to get them to delegate that authority." She noted that in the 21 years since those deals were approved, Congress has awarded trade promotion authority to a president for a total of only five years.

"For Obama, it’s particularly tricky, because that big power grab would be used for this agreement that is basically a Trojan horse for every kind of extreme corporate proposal that could not get passed in the sunshine of public debate," she said.

The White House rejects the characterization, arguing that the Trans-Pacific Partnership would raise standards across the board. Perez said officials were incorporating lawmakers’ concerns about important elements of the agreement — like the need for stronger and quicker enforcement measures — into the continuing international negotiations.

"The guidance from the president has been very clear: I want the best agreement that’s going to protect American workers, provide decent hours and wages, and address both environment and labor conditions," Perez said.

Republicans and centrist Democrats strongly support Obama’s trade agenda. But given the bitter partisan divisions in Washington and Obama’s aggressive use of executive action in recent months, it is unclear how unified Republicans will be in support of his trade initiatives.

"This is the rare issue in which he’s going to have more problems with the Democrats than with the Republicans because he is working against the wishes of key elements of the Democratic coalition," said David Karol, an associate professor at the University of Maryland who studies trade policy. "But some Republicans also just don’t want to give President Obama a victory, period, no matter how much they may like the policy."

At the same time, business groups that are highly motivated to win approval of the new agreements are pressing Obama to take a more active role in selling his trade policies in Congress.

"He’s going to need to really step out a lot more and make the case for why this is important," said Christopher Wenk, senior director of international policy at the U.S. Chamber of Commerce. "There are a lot of Democrats who want to be helpful on this, but they’re waiting for the president to be out there leading — they need some cover."

Democratic critics are becoming increasingly vocal about their opposition to Obama’s stance. Some of them are popular with members of the party base who will play a major role in choosing the 2016 presidential nominee.

Sen. Elizabeth Warren of Massachusetts, a favorite of the Democratic Party’s liberal wing, told a labor forum Wednesday that trade agreements were among the poor choices that had "left America’s middle class in a deep hole."

Those concerns are fueling the opposition to the trade authority that Obama wants. It typically allows agreements to be considered by Congress on an expedited basis, with no opportunity for lawmakers to make changes.

"The reality is that all of us here support the president and a lot of the president’s agenda," Rep. Donna F. Edwards, D-Md., said at the news conference. "But we also each represent a congressional district that is in jeopardy of losing millions of jobs because of a bad trade deal."

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