UPDATE: The House of Representatives voted narrowly to grant Barack Obama trade-promotion authority (TPA) on June 18th. Just 28 Democrats supported the president. The bill now moves to the Senate.

THE world economy is undergoing revolutionary changes, John F. Kennedy told Congress in 1962. If America chooses to lead, it can shape new rules for an era of free trade and healthy competition. The Democrat who occupies the White House today makes the same case in defence of the Trans-Pacific Partnership (TPP), a 12-country trade pact. Barack Obama may yet prevail over the opposition of his own party as he seeks “fast-track” trade-promotion authority (TPA, confusingly)—the right to negotiate TPP and other trade agreements which Congress could then approve or reject, but not amend. However, the fight over TPP has already dented America’s leadership credentials, to say nothing of Hillary Clinton’s (see article).

On June 12th Democrats in the House of Representatives, egged on by trade-union bosses, led a revolt that, temporarily at least, has derailed Mr Obama’s chances of winning fast-track authority. Its opponents call the TPP deal a dangerous sequel to earlier trade accords, which they blame for sending factories from the American heartland to low-cost countries far away. (Never mind that, in a tactic to thwart Mr Obama, they voted against a training scheme for workers whose jobs are lost to foreign competition.) Tribunes of the populist left, such as Senator Bernie Sanders of Vermont, have used the fight against TPP to revisit long-standing grievances about the power of Wall Street banks and big business. Nancy Pelosi, the Democratic leader in the House, has called for wholly new ways to regulate globalisation, perhaps under the auspices of the UN.

Such attacks are off-target. The threat to America from low-wage manufacturing hubs is exaggerated: killing TPP would not bring factory chimneys and steel mills back to blighted Rust Belt towns. New markets among the 12 TPP countries are worth having: between them these Pacific Rim nations account for 40% of global economic output. And the thrust of TPP is to open up sectors such as services, where America enjoys a comparative advantage. As for Ms Pelosi’s ideas, they are pure grandstanding. There is no conceivable congressional majority for handing trade powers to an international body.

In JFK’s shadow

At least she is being less weaselly than Mrs Clinton, the front-runner to win the Democratic presidential nomination. As Mr Obama’s Secretary of State, Mrs Clinton repeatedly hailed TPP’s importance and its “gold standard” quality as a trade pact, with unprecedented protections for workers’ rights and the environment. Yet before the vote in Congress she was silent; after the revolt she urged Mr Obama to listen to House Democrats and seek to drive a harder bargain with foreign countries. This is not heir-to-Kennedy behaviour.

Examples of political dysfunction in Washington are ten-a-penny, but the row over TPP risks undermining American leadership in Asia and beyond. One reason is that the trade deal may fizzle. Without fast-track authority, every clause in a TPP agreement will be open to congressional tweaking; that makes negotiations practically impossible. If TPP crumbles, Mr Obama’s talk of a pivot to Asia will ring hollow.

Even if Mr Obama does eventually win the fast-track fight, the saga has already imposed costs. To win support for TPP, the president has made the pact sound like a way to curb the rising power of China, which is not part of the talks. This comes after a ham-fisted attempt to squash an initiative by China to set up an Asian infrastructure bank. Yet TPP would be worth more if China was part of it and America’s long-term interests are best served by knitting China into a rules-based economic system. TPP, in other words, ought to be a vehicle for American economic leadership. Instead it risks being a case study in the very insularity that JFK warned about.