Jonathan Tasini has been a frequent commentator on CNN and is a Bernie Sanders supporter. He unsuccessfully challenged Hillary Clinton in the Democratic Senate primary in New York in 2006. He is the author of " The Essential Bernie Sanders and His Vision for America ," president of the Economic Future Group and the publisher/editor of Working Life. The opinions expressed in this commentary are his own.

(CNN) President John F. Kennedy once said , "The great enemy of the truth is very often not the lie, deliberate, contrived and dishonest, but the myth, persistent, persuasive and unrealistic." It's quite an apt observation, considering the horrendous policy position on the issue of the Trans-Pacific Partnership now contained in the draft Democratic Party platform -- a position that puts the party at electoral peril in November and, more important, leaves it at odds with the interests of working people, one of its most important constituencies.

This past Friday, at the party's public hearings in St. Louis , representatives of Bernie Sanders' campaign attempted to insert a single line into the trade section of the platform: "It is the policy of the Democratic Party that the Trans-Pacific Partnership must not get a vote in this Congress or in future sessions of Congress."

It failed on a straight "party line" vote, with every one of Hillary Clinton's representatives giving the thumbs down on the amendment. This development is a gift to Donald Trump's jeremiad against bad trade deals.

There is still time to adjust course. The full platform committee will meet in Orlando next week to consider the draft document. Elected labor delegates represent a significant percentage of delegates overall.

Regardless of whom they will support when the roll call comes to determine the party's nominee, they could, and should, unite to support the Sanders' language on TPP. They would then stay true to labor's stated position -- and strengthen the Democratic Party's potential for electoral victory against Donald Trump in November.

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Count me as one of those people who never believed in Clinton's newfound opposition to the TPP, which she previously had called the "gold standard" for trade pacts ( as a recent video confirms ). Even Tom Donohue, president of the U.S. Chamber of Commerce, publicly reassured his members that Clinton would be back in the fold if she became president.

She has consistently supported so-called "free trade" while Sanders has opposed every such deal dating back to Bill Clinton's NAFTA. But, her campaign wisely understood she could not hope to capture the party's nomination running as the true corporate-friendly Democrat she is.

Regardless of whether Clinton is truly on board with the TPP, she and her delegates should embrace the inclusion of anti-TPP language in the Democratic Party platform.

Whether they have supported Clinton or Sanders in the primary contests, virtually all unions oppose the TPP. And trade is not some secondary topic that will fade away as we enter the general election.

For a quarter of a century, the labor movement has wisely opposed NAFTA-style deals, which set up rules protecting corporate rights, with meaningless verbiage about labor and environmental safeguards slapped on as a microscopic Band-Aid to try to mollify critics.

Since NAFTA's passage, hard-working Americans have watched millions of unionized jobs evaporate. Workers, who once made a living wage, now labor for substandard pay with no benefits , partly because they are afraid to demand more in the face of corporate threats to close up shop and move to another country with slave-like wages.

The current low-demand economy, with its hiccupping anemic growth, can, in part, be traced to so-called "free trade" -- too many people have jobs that just don't pay enough money to meet expenses, not to mention save anything for retirement.

To be clear, Barack Obama's trade agenda will only advance because it is supported by the bulk of the Republican members in Congress. The majority of the Democratic caucus in the House and Senate oppose the TPP, as do a majority of Democratic Party voters.

So, effectively, to be in step with Hillary Clinton's true views on trade, the majority on the drafting committee is shilling for corporate America at a time when millions of people are clamoring for economic policies that support the people. Astonishing.

JUST WATCHED Sanders hits Clinton over trade Replay More Videos ... MUST WATCH Sanders hits Clinton over trade 01:28

The greater danger lies ahead. I have been warning for many months that Donald Trump's assault against NAFTA-- a position contrary to his party's mainline orthodoxy -- will give him traction in critical swing states like Ohio, Michigan, Pennsylvania and other communities hurt by NAFTA-style trade.

It is beyond mystifying why Democrats would hand an unhinged, dangerous man, who is alienating people of all walks of life, a political lifeline that affords him a megaphone that we should own. Moreover, it would be a deep blow to Obama's legacy if his misguided pursuit of the TPP, in opposition to his own party's rank and file, paves the way for a Trump presidency.

Failing a change in Orlando, this is an issue that is worth a knock-down, drag-out public fight on the convention floor. Sweeping the TPP under the rug in the name of some false unity would be a great disservice to our country. Where one stands on the TPP is not simply an item on some check list but a fundamental expression of values and what the party stands for.

Politics often gives us great ironies. When I pulled up the AFL-CIO web page on its TPP opposition, up popped a web ad supporting Clinton. With her smiling face, it featured a quote from her: "Unions helped build the great middle class in history."

That is absolutely true. I can't imagine that anyone envisioned the jarring visual contrast between that quote casting a shadow over a policy that will eviscerate unions and the middle class.