There are a number of reasons why Elizabeth Warren, popular with Democrats though she may be, would make a lousy vice-presidential pick for Hillary Clinton. Sure, she’s great on the stump, and has launched several blistering attacks on Donald Trump as Clinton’s personal anger translator. But in most ways that matter, the two are hopelessly mismatched. For one, Warren has a problematic habit of criticizing Clinton’s most loyal donors, a fact that has not been overlooked by the Wall Street moneymen bankrolling her campaign. As if that were not enough to dampen the veepstakes buzz surrounding Warren, who is among a small handful of names that are reportedly on Clinton’s short list, the Massachusetts senator announced Thursday that she is embarking on a major nationwide campaign to derail a major trade deal being pushed by the White House and that Clinton supported as secretary of state.

“It will be open season on laws that make people safer but that cut into corporate profits.”

In a newly released video Warren sounds more in line with Trump than the woman vetting her for vice president. Just shy of five minutes in length, the video features the former Harvard Law professor slamming the Trans-Pacific Partnership, the controversial 12-nation trade pact that Clinton has only recently turned her back on amid backlash. “America shouldn’t be signing lousy trade deals. Period,” the popular Massachusetts senator says in the video, echoing Trump’s recent, frequent attacks on the former secretary of state.

Warren calls on progressives to help her stop the trade deal in the video, which was posted by activist group CREDO. “Here’s the problem: T.P.P. isn’t about helping American workers set the rules; it is about letting giant corporations rig the rules,” she levels. The senator’s message focuses on one specific provision of the trade deal, the Investor-State Dispute Settlement, which would allow industry giants to curtail traditional legal processes in favor of arbitration, potentially threatening public safety regulations. “It will be open season on laws that make people safer but that cut into corporate profits,” Warren says. Because Congress has to vote either yes or no on the trade deal, without the opportunity to amend the deal, Warren is pushing for activists to pressure their representatives to thwart the deal, which Barack Obama has spent much of his presidency working to pass as part of his so-called “pivot” to Asia.

Throughout the election cycle, Clinton has faced criticism for her support of the T.P.P., which was drafted while she was working in the State Department, and has gradually turned against it. While she previously called the T.P.P. “the gold standard,” the former New York senator now says the agreement isn’t up to her standards, and has argued that the deal—which has been seven years in the making—should be renegotiated. During a primary debate last fall, Senator Bernie Sanders knocked Clinton for her tepid support of T.P.P. “We shouldn’t renegotiate the Pacific trade proposal. We should kill this unfettered free-trade agreement, which would cost us nearly half a million jobs.” More recently, Trump has added the T.P.P. to his Rolodex of Clinton attacks, and labeled the deal, “a rape of our country,” at an event in Ohio last week.

Warren, in other words, is not the first Democrat (or Republican) to attack the T.P.P., highlighting Clinton’s flip-flop. But it’s not the first time the fiery politician has taken a stance that clashes with Clinton’s policy platform, either. Just last week, Warren unloaded on Silicon Valley for what she claimed are anti-competitive practices, and singled out a handful of the same tech titans that Clinton had been busy currying favor with less than 24 hours earlier. If the senator is still in the running for Clinton’s ticket, her anti-T.P.P. tirade won’t do the presidential hopeful any favors. It also doesn’t inspire confidence in her ability to help Clinton build a unified front in the battle against Trump, no matter how much she inspires the Sanders wing of the party. The last thing any presidential nominee needs is a No. 2 who doesn’t know how to fall in line.