Senate Majority Leader Harry Reid of Nevada told reports that he opposed the “fast track” legislation considered necessary for potential treaties with Pacific and European nations to stand a chance of passage in Congress. (J. Scott Applewhite/AP)

Senate leaders from both parties delivered a blow to a core piece of President Obama’s economic agenda only hours after the State of the Union speech, casting doubt on whether he can push a massive new trade program through the current Congress.

Senate Majority Leader Harry M. Reid (D-Nev.) told reporters on Capitol Hill that he opposed the “fast track” legislation considered necessary for potential treaties with Pacific and European nations to stand a chance of passage in Congress.

Legislation was recently introduced in both chambers, but a possible change in leadership of the Senate Finance Committee — Chairman Max Baucus (D-Mont.) has been nominated as U.S. ambassador to China — already threatens to slow its progress.

Reid on Wednesday urged the administration “to not push this right now.”

“I’m against fast track,” Reid said.

His comments followed a State of the Union speech in which Obama focused on economic issues but gave little space to a raft of trade legislation and free trade treaties his Cabinet has been working to complete.

That drew a rebuke from Sen. Orrin G. Hatch (R-Utah), who in remarks at the U.S. Chamber of Commerce said that the administration “needs to do better” in building congressional support for a trade package.

“So far I’ve been underwhelmed,” he said, chiding Obama for not calling on Democrats directly in his speech to get behind the pending trade bill.

Reid’s remarks in particular are a sign of the hurdles the administration faces in pushing through Congress what would amount to the most ambitious set of free trade agreements in a generation — encompassing Europe, Japan and other nations, and covering the bulk of global economic activity.

The agreements have been promoted by major business groups and cast by U.S. negotiators as a way to shape global regulations and trade patterns in favor of industries important to future U.S. growth and employment.

“Leader Reid has always been clear on his position on this particular issue,” a White House official said. “As the president said last night, he will continue to work to enact bipartisan Trade Promotion Authority to protect our workers and environment and open markets to new goods stamped ‘Made in the USA,’ and we will not cede this important opportunity for American workers and businesses to our competitors.”

Opponents of the trade agreements — and of the fast track legislation needed to clear the way for their approval in Congress — have been organizing steadily around the issue, and in recent weeks have intensified their argument that past trade agreements have hurt U.S. workers more than they have helped.

In a conference call Wednesday, labor and environmental groups said that a recent poll they commissioned showed deep skepticism about trade agreements, and strong sentiment against fast track legislation because it gives the president “too much power.”

Fast track privileges have been available at some point in the administration of every president since Gerald R. Ford. But opponents of the proposed Transpacific Partnership and the separate Transatlantic Trade and Investment Partnership view the potential defeat of the fast track bill as a step toward blocking the proposed agreements in the future.

Without fast track, the treaties — once negotiated among the nations involved — would be subject to extensive congressional debate and potentially crippling amendments.

Larry Cohen, president of the Communications Workers of America and a vocal opponent of the trade legislation, said that between the labor, environmental and other groups that are active on the issue, “voters will be energized. . . . It is small business. It is everybody. Americans are saying, ‘What kind of future do we want? We don’t want a trillion-dollar trade deficit.’ ”