The head of the nation's largest labor organization on Tuesday slammed President Obama's trade push and vowed to block efforts in Congress to help the administration finalize a major free trade pact in the Asia Pacific.

"We are going all out to oppose it," AFL-CIO President Richard L. Trumka told reporters about bipartisan talks on Capitol Hill over a bill to grant the administration "fast-track" authority to complete the 12-nation Trans-Pacific Partnership.

"This will trump any debate out there," Trumka said. "There is such a dramatic impact on the standard of living and a lowering of wages and a loss of jobs -- this will have a major impact, and we will not forget this vote for a long time."

The opposition from organized labor is not unexpected, but the AFL-CIO's stepped-up campaign comes at a critical moment in the administration's effort to shore up enough Democratic votes on Capitol Hill to get the TPP deal through Congress by year's end. Last week, Senate Finance Committee Chairman Orrin Hatch (R-Utah) said a fast-track trade bill would be delayed until April after talks with Sen. Ron Wyden (D-Ore.) over the specific language of the legislation hit an impasse.

Trumka interpreted the delay as a sign that the opposition is successfully sowing doubt about the trade talks between the United States, Japan and 10 other Pacific Rim nations, which critics are concerned will help multinational corporations at the expense of workers. Though the AFL-CIO has not taken a position on the TPP, the organization is opposing legislation that would allow the Obama administration to strike a final deal without lawmakers being allowed to amend the terms before a vote.

Although Republicans leaders are supporting the fast-track powers, Trumka warned Democrats that "this will be an Obama bill. It will adversely affect the way working people view this administration and those in the Democratic Party for a long time."

And he vowed to make the vote a campaign issue next year for lawmakers. "He isn't running again," Trumka said of Obama. "They are."

Administration officials have said they need fast-track authority to give other nations confidence that their final offers at the negotiating table will not be altered by Congress. The TPP is one of the largest free trade deals in U.S. history, representing countries with 40 percent of the world's gross domestic product, and the administration is eager to bring the pact to a close this year, before the 2016 presidential race makes it more difficult.

Obama and his advisers have said the deal -- which would lower tariffs, set up new rules governing intellectual property and procedures for mitigating disputes between nations and multinational corporations, and establish new labor and environmental standards -- is important to maintain the United States's economic influence in the face of increasing competition from China, which is not part of the negotiations.

But Trumka said workers are skeptical of such pacts, citing the impact of the North American Free Trade Agreement negotiated by the Clinton administration with Mexico and Canada in the early 1990s.

"Bill Clinton still gets screamed at about NAFTA by working people," Trumka said. "I still get accosted about it because they say it's a Bill Clinton bill. Even he has come to understand that NAFTA is not the panoply it was supposed to be. ... There's no reason to believe that TPP will be a break from the NAFTA model. I haven't seen it yet."