The Senate voted Wednesday to give President Barack Obama "fast track" authority to negotiate trade deals—one of the final steps in a long political battle that pitted the White House against House Democrats.
The bill—which passed 60-38 in the Senate—will be sent to the president's desk later this afternoon, but it was not immediately clear when he would sign it.
Unions and most congressional Democrats say free-trade deals cost U.S. jobs and reward countries that pollute and mistreat workers. Obama and most Republican leaders say U.S. products must reach broader markets.
After killing one version of fast track (also known as Trade Promotion Authority, or TPA), the House eventually voted last week to pass the measure.
The Senate plans to vote on three other trade-related bills. One would extend a job retraining program for workers displaced by international trade. That program requires House approval, too.
On Tuesday, Senators voted 60-37 to streamline the debate process—a key victory for the Obama-backed measure.
Senate passage Wednesday of fast-track authority boosts Obama's hopes for a 12-nation Pacific-rim trade agreement. Members include Japan, Malaysia, Mexico and Canada.
In addition to the traditional arguments for trade deals, administration officials and many Republicans contend that the so-called Trans-Pacific Partnership would help underscore the U.S. pivot toward Asia—and establish Washington's system in a part of the world increasingly influenced by Chinese interests.
TPA means that the White House can present its finalized trade deals to Congress, and the legislature is only given the option of voting for or against the agreement—not amending the terms.
Most trade experts interviewed by CNBC say that would-be trade partners are unwilling to sign onto an agreement if the president isn't given fast track status: They fear that Congress would otherwise disassemble any hard-fought terms. Administration officials, however, have said they would not be wholly stymied if TPA fails.
The TPP, potentially a legacy-defining achievement for Obama, would be the biggest free trade agreement in a generation. It would cover 40 percent of the world economy and raise annual global economic output by nearly $300 billion.
Negotiators say a deal on the TPP, which would open new markets for U.S. exporters such as Caterpillar and Microsoft, could be wrapped up within weeks once countries are sure U.S. lawmakers will not pick the deal apart afterward.
—Reuters and The Associated Press contributed to this report.