Environmentalists oppose it. So do labor unions, medical professionals, and major religious groups, as well as every leading presidential candidate.

So why hasn't the Democratic Party gone on record opposing the Trans Pacific Partnership (TPP)?

That's what Bernie Sanders wants to know.

Noting that the deal "is opposed by virtually the entire grassroots base of the Democratic Party," Sanders said Sunday he will reintroduce an amendment rejecting the TPP at next weekend's full Democratic Platform Committee meeting in Orlando, Florida.

In an op-ed published in the Philadelphia Inquirer, Sanders praised the platform drafting committee for including "some very positive provisions" in the final draft released Friday.

"At a time when huge Wall Street financial institutions are bigger now than they were before the taxpayers of this country bailed them out, the platform calls for enacting a 21st-century Glass-Steagall Act and for breaking up too-big-to-fail banks," Sanders wrote.

"The platform calls for a historic expansion of Social Security, closes loopholes that allow corporations to avoid paying taxes, creates millions of jobs rebuilding our crumbling infrastructure, makes it easier for workers to join unions, takes on the greed of the pharmaceutical companies, ends disastrous deportation raids, bans private prisons and detention centers, abolishes the death penalty, moves to automatic voter registration and the public financing of elections, eliminates super PACs, and urges passage of a constitutional amendment to overturn Citizens United, among many other initiatives," he continued—all provisions where Sanders' influence was in evidence.

However, Sanders wrote, "there were a number of vitally important proposals brought forth by the delegates from our campaign that were not adopted." These included a national ban on fracking, a carbon tax, and clear language on corporate-friendly "free trade" agreements like the TPP.

To that end, Sanders said he will offer an amendment in Florida "to make it clear that the Democratic Party is strongly opposed to the Trans-Pacific Partnership" and to ensure the deal doesn't come up for a vote during the lame-duck session of Congress.

"My hope is that a grassroots movement of working people, environmentalists, and human-rights advocates will work with us to demand that the Democratic Party include these initiatives in the platform to be adopted by the full committee in Orlando," he wrote.

As Sanders and others observed last week, by tacitly backing the TPP, the drafting committee was not only working against the party, but undermining Clinton's own stated position.

Indeed, Sanders wrote in the Inquirer op-ed:

Frankly, I do not understand why the amendment our delegates offered on this issue in St. Louis was defeated with all of Hillary Clinton's committee members voting against it. I don't understand that because Clinton, during the campaign, made it very clear that she did not want to see the TPP appear on the floor during the lame-duck session. If both Clinton and I agree that the TPP should not get to the floor of Congress this year, it's hard to understand why an amendment saying so would not be overwhelmingly passed.

The full 187-member Platform Committee meets in Orlando ahead of the Democratic National Convention, which will ratify the platform, at the end of the month.