The 66-30 vote brought Mr. Bush a giant step closer to a prize he has sought since taking office 16 months ago and cleared the way for a complex negotiation with the House on a final compromise.
The Senate action "sends an important signal to our trading partners that we are committed to free and open trade," Mr. Bush said in a statement released while he was on an overseas trip to Europe and Russia.
Enactment of a final House-Senate compromise, he said, "will give me the flexibility I need to secure the greatest possible trade opportunities for American workers, consumers, families and farmers."
In a reprise of three weeks of Senate debate, supporters hailed the measure while detractors attacked it as an extension of a failed trade policy that has decimated key industries such as textiles and steel.
"New Mexico's economy could benefit tremendously from agreements that open up overseas markets," said Sen. Jeff Bingaman, D-N.M., who authored several initiatives contained in the bill. "These agreements could mean new markets for our farmers and ranchers, the state's high-tech sector and even the arts community."
Max Baucus, D-Mont., chairman of the Senate Finance Committee, said: "It's a landmark bill because it not only modernizes our trade policy but it also is balanced with a quite progressive trade adjustment assistance to Americans who are dislocated on account of trade."
The measure "empowers our nation to get the best bargain we can at the negotiating table," said Sen. Charles Grassley, R-Iowa, adding it would result in open markets for American agriculture and manufacturing products.
But critics said that was an illusion. "There never has been any such thing as free trade and never will be," said Ernest Hollings, D-S.C., who listed a series of trade barriers erected by foreign nations that he said undermine existing agreements. "Almost like world peace. You strive for it. You strive for it. It won't happen in my lifetime, in your lifetime."
The bill represents a compromise between the White House's call for enhanced negotiating power and a demand by Senate Democrats for health care and other benefits for workers who lose their jobs to import competition.
It would give Mr. Bush the authority that most chief executives have had for the past quarter-century to negotiate international trade deals subject to a yes-or-no vote in Congress. The last president to wield that power, President Clinton, failed to win a renewal from the GOP-controlled Congress when it expired in 1994.
To the distress of the White House, a Senate-passed provision permits lawmakers a separate vote in cases that undermine existing anti-dumping laws. Administration officials have threatened a veto if it is included in the final legislation, and pledged to work for its removal in the final compromise.
The assistance provisions include the first-ever health care subsidies for laid-off workers, as well as expanded job re-training benefits, at an overall cost of $10 billion to $12 billion over the next decade.
Secondary workers — those who supply goods to manufacturers, for example — would be eligible for assistance for the first time, as would family farmers, ranchers, fishermen and employees of firms that move production facilities overseas.
The bill also includes a pilot program of wage insurance. Workers who lose jobs due to imports and find lower-paying employment would receive a federal wage supplement equal to half the difference between their old and new salaries. At the same time, they would have to forfeit eligibility for job retraining and other trade assistance benefits.
Additionally, the measure renews an expired program of low tariffs for selected products from the Andean nations of Colombia, Peru, Ecuador and Bolivia.
The bill was molded during nearly three weeks of debate in which Democratic opponents filibustered in an unsuccessful attempt to block passage, then GOP trade supporters filibustered successfully to prevent Democrats from expanding the trade assistance programs even further.
The result was a compromise that drew 68 votes in a test of strength on Thursday, making clear it would pass. The vote on final passage was close to that, with 41 Republicans, 24 Democrats and one independent supporting the bill while 25 Democrats and five Republicans opposed it.
At the same time, maneuvering was well under way for the House-Senate negotiations expected to take place this summer.
While the White House said it would insist on removal of the provision giving Congress additional authority to vote on trade deals, more than 100 Democrats issued a letter calling for its inclusion in the final bill.
Without it, said Rep. Robert Matsui, D-Calif., the president "will be in a position to change American domestic laws by going through the World Trade Organization"
Even so, die-hard opponents spent much of the day Thursday assailing the legislation.
American trade policy is "not working, this is a failure," said Sen. Byron Dorgan, D-N.D., brandishing a graph that showed a dramatic increase in the nation's foreign trade deficit.
"This is a massive failure. Our trade strategy is drowning America in red ink."