Elizabeth Warren, the famously fiery populist senator from Massachusetts, has a reputation for having a bit of a reverse-Midas touch, when she wants to: if she decides she is against something, it often turns to smoke.

The latest subject of her withering glare? In a letter to supporters Thursday afternoon, Warren decried a sub-chapter in the Obama administration’s proposed trade deal, the Trans-Pacific Partnership, that would allow companies to sue foreign countries through an extra-judicial tribunal made up of three for-profit arbitrators.

If that sounds a little hard-to-follow, that’s because it is. But Warren’s street cred with liberals is strong enough that they tend to take her lead even when the argument can’t be summed up in a simple bumper sticker slogan.

Provisions for these tribunals — known as an investor-state dispute system, or ISDS — have appeared in more than 3,000 trade deals, including the North American Free Trade Agreement, since the 1950s, according to Jeff Zients, the director of the National Economic Council.

But Warren argues that it’s different this time around. For one, the Trans-Pacific Partnership is enormous. It includes the U.S. and 11 other countries, including Japan, Australia and Chile, oversees a whopping 40% of the world’s total annual GDP, and it’s irreversible: once we’re in it, there’s no getting out.

And for another, she claims that ISDS isn’t what it used to be. Two decades ago, when NAFTA was ratified, multi-national corporations were smaller and less powerful than they are today. Her case is that as those interests have gotten bigger and bigger, they’ve gotten more litigious: in the four decades from 1959 to 2002, there were fewer than 100 ISDS cases world wide. Between 2010 and 2013 alone, there were more than 200.

“Recent cases include a French company that sued Egypt because Egypt raised its minimum wage, a Swedish company that sued Germany because Germany decided to phase out nuclear power after Japan’s Fukushima disaster, and a Dutch company that sued the Czech Republic because the Czechs didn’t bail out a bank that the company partially owned,” she wrote in a Washington Post op-ed this winter.

In February, John Oliver, the Comedy Central comedian and host of Last Week Tonight who also holds sway with liberals, mocked an effort by the tobacco company, Philip Morris, to use ISDS to reverse public health regulations in Uruguay’s designed to reduce the smoking rate.

President Obama, backed by most Republicans, a majority of Democrats, and the powerful corporate interest groups, like the U.S. Chamber of Commerce and the Business Roundtable, says Warren is just plain wrong. (He’ll be at Nike’s headquarters in Oregon on Friday explaining why the TPP is great.) ISDS is necessary, the deal’s backers argue, to ensure the corporations feel comfortable making direct foreign investments in other countries — particularly those with less well developed court systems.

But policy arguments aside for a moment, will the famous Warren touch work this time around?

In the past, Warren has been successful in taking down very narrow targets. Last fall, she set her sights on Antonio Weiss, the White House’s nominee for Treasury undersecretary for domestic finance, and by January, he’d bowed out. Before that, Warren helped doom Obama’s plan to nominate former Treasury Secretary Larry Summers to head the Federal Reserve.

But Warren’s also had some off-days. She failed, for example, in her effort last December to quash Congress’s unwieldy continuing resolution and omnibus bill — nicknamed the “Cromnibus” — which included provisions that unwound financial regulations.

And the Trans-Pacific Partnership, for better or worse, may have more in common with the latter than the former. Like the Cromnibus, the TPP is huge, unwieldy, and also includes provisions that many Democrats will like.

Plus, there are technical difficulties. If Congress passes what’s known as the “fast-track” bill next week — it’s unclear if they currently have the votes they need — there won’t be any room for debate about which parts to keep, rewrite, amend or scrap. The fast-track bill binds Congress into an up or down vote on the final version of the trade deal.

And if it comes down to a simple “yes” or “no,” Warren’s famous touch, however powerful, might not be enough.

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Write to Haley Sweetland Edwards at haley.edwards@time.com.