The Senate voted 62-37 to give this president and the next so-called trade promotion authority, ensuring that Congress could not amend or filibuster any trade accord negotiated over the next three-to-six years, though lawmakers could reject it.WASHINGTON — President Obama moved closer to expanded trade negotiating power Friday night after the Senate passed hard-fought legislation that would help complete the most ambitious trade accord in a generation. The deal would link 12 nations on either side of the Pacific into a trading bloc that would encompass 40 percent of the global economy.

Senator Orrin G. Hatch of Utah, chairman of the Senate Finance Committee and usually a foe of Mr. Obama’s, called it “likely the most important bill we’ll pass this year,” adding, “it shows that when the president is right we will support him.”

The legislation still faces a difficult path in the House, where almost every Democrat is dug in against Mr. Obama’s top legislative priority, and where a rebellion may be brewing among the most conservative Republicans. Opponents say the measure will only hasten the exodus of manufacturing jobs to low-wage countries like Vietnam, depressing wages for the working class as it buoys the fortunes of the affluent.After the vote, Mr. Obama said, “I want to thank Senators of both parties for sticking up for American workers by supporting smart trade and strong enforcement, and I encourage the House of Representatives to follow suit.”

“Do we want to live in an America where the middle class is wiped out?” asked Senator Jeff Merkley, Democrat of Oregon, presaging criticism to come.

But Mr. Obama’s Senate victory was significant and convincing. It brought the president one step closer to securing the Trans-Pacific Partnership, a legacy-defining trade accord linking countries from Canada to Chile and Australia to Japan, cementing at least the economic part of Mr. Obama’s so-called pivot to Asia. Trading partners have said they cannot complete negotiations without trade promotion authority because they cannot make their own politically difficult concessions, knowing Congress could tamper with them.

But the legislation goes still further. It extends that negotiating power for three years, with a possible extension for another three. That would mean the next president will enjoy most of the authority and it would ease passage of another major trade accord under negotiation with the European Union, expected to be finished in 2016.

Twice, Democratic opponents nearly derailed the trade promotion bill on procedural votes. On Friday night, supporters of the bill narrowly defeated a bipartisan amendment that would have demanded that future trade agreements crack down on countries that intentionally devalue their currencies, a measure that again could have derailed the bill. The amendment, by Senators Rob Portman, Republican of Ohio, and Debbie Stabenow, Democrat of Michigan, fell 48 to 51.

In the end, 14 Democrats sided with the president over Senate Democratic leadership to ensure passage.

“By passing this legislation, we can show we’re serious about advancing new opportunities for bigger American paychecks, better American jobs and a stronger American economy,” said Senator Mitch McConnell of Kentucky, the majority leader, who forged a rare alliance with the president to push the legislation.

Senator Harry Reid of Nevada, the Democratic leader and stalwart Obama ally, denounced the bill as “a handout for multinational corporations” that “does nothing for the middle class.”

Final passage came only after the bill ran a gantlet of amendments that could have derailed it — or at least made passage through the House much more difficult. The nail-biter was over the currency provision co-sponsored by Mr. Portman, a former United States trade representative in the George W. Bush White House. It would have demanded that future trade agreements include an enforceable crackdown on countries that intentionally depress their currencies to make their exports cheaper and American imports more pricey.

Jacob J. Lew, the Treasury secretary, had called on Mr. Obama to veto the trade promotion bill if the currency amendment was attached, fearing it could have backfired and empowered trading partners to challenge American fiscal and monetary policy making.

The Senate also voted down an amendment by Senator Elizabeth Warren, Democrat of Massachusetts, which tried to remove from the Pacific accord a chapter that would give corporations the power to challenge governments that take actions that affect the value of their investments. Ms. Warren maintains the so-called investor-state dispute settlement process could jeopardize American banking regulations and future environmental protections.

Also defeated was an amendment requiring congressional approval before any country not among the original 12 could join the Pacific partnership, and a Republican effort to strike assistance to workers who lose their jobs because of trade agreements.

The trade battle now shifts to the House, where passage was always expected to be more difficult. Only 17 Democrats have publicly declared their support, well short of the 30 that Republican leaders say they need. Senior House Democrats are adamant that trade deals dating to the North American Free Trade Agreement have cost hundreds of thousands of jobs and depressed wages for workers competing with low-wage countries.

More ominously for supporters of trade are the rumbles on the right that could cost the president Republican votes. The decision by Senator Ted Cruz, Republican of Texas and a Tea Party favorite, to back trade promotion has insulated the bill from Republicans inclined not to give Mr. Obama authority for anything. But that protection may be fraying.

On Friday, Rush Limbaugh became the latest conservative voice to pressure lawmakers.

“Since it’s an Obama deal, the odds are the United States is going to take it in the shorts, as we have on so much of the Obama agenda, both domestic and foreign policy,” he announced on his radio show.