Following a brief feint in which the White House masterfully exploited the servility of congressional Republicans to create the impression that Barack Obama was still firmly in command of the country’s destiny, the revolt of liberal lawmakers over a proposed free trade has made it clear that the president is very much a lame duck.

The internecine fight among Democrats over the Trans-Pacific Partnership has elevated Sen. Elizabeth Warren (D-MA) to the status as chief liberal opponent of a Democratic White House. “The government doesn’t want you to read this massive new trade agreement. It’s top secret,” Warren said in a statement responding to the president who singled her out as his central adversary. “Why? Here’s the real answer people have given me: ‘We can’t make this deal public because if the American people saw what was in it, they would be opposed to it.'”

“If the American people would be opposed to a trade agreement if they saw it, then that agreement should not become the law of the United States,” her statement continued.

In an appearance on MSNBC with Rachel Maddow on Wednesday, Warren added that she was worried that the authority Obama is seeking from Congress that would allow him to bypass the legislature to craft and enact trade deals could be misused by future presidents. Whomever might that be?

The fight over the TPP has showcased Hillary Clinton’s limitless capacity for inconsistency. She praised it as recently as 2014, but Clinton has since expressed reservations about the TPP when it has become apparent that the progressive wing of the Democratic Party is suspicious of the deal’s effects on American labor.

Some contend that this is Warren’s sweet spot; she prefers to advocate for causes in which she believes rather than selling herself as a candidate. But not everyone shares this sentiment. As Clinton’s mounting scandals continue to dominate the news cycle and drag Clinton’s electoral prospects down with them, The Atlantic’s David Frum anticipates that Warren will have little choice but to enter the 2016 race as the progressive champion.

Frum is skeptical of the notion that Warren can be much of a force in the Senate as a junior senator unless she retains her current role as something of a spoiler of pragmatic Democrats’ ambitions. Moreover, Chris Christie’s experience suggests that popularity in politics is fleeting, and Warren’s window to win her party’s nomination is rapidly closing.

And if Hillary Clinton wins in 2016, what role for Warren then? President Clinton will face Republican majorities in both House and Senate. Like her husband in the 1990s, she’ll have to do business with them—and squash any Democrat who objects. If Hillary Clinton loses in 2016, Warren’s role in the Senate will quickly be eclipsed by the next generation of Democrats competing for their chance in 2020. By then, Warren will be nearly 70, older than most presidential candidates, even in our geriatric political era.

“If Elizabeth Warren did seek the Democratic presidential nomination, she’d seize the party and the national agenda. Rank-and-file Democrats seethe with concern about stagnant wages, income inequality, and the malefactions of great wealth,” Frum noted. “Left to her own devices, Hillary Clinton will talk about none of that.”

“If a politician expresses ideas that are shared by literally tens of millions of people—and that are being expressed by no other first-tier political figure—she owes it to her supporters to take their cause to the open hearing and fair trial of the nation,” he concluded. “It would be negligent and irresponsible not to do so.”

Frum makes a good case, but the only factor he did not appear to consider is the possibility that Warren is as career-minded and ambitious as the next politician. If she is a truly selfless ideologue, she might take Frum’s advice and take a stab at the queen. If she misses, her supporters will find her sacrifice admirable and will respect her for enduring the subsequent consequences. And there will be consequences.

As anyone who didn’t back Clinton in 2008 and found themselves on her “enemies list” will attest, the former first family has a long memory. An attempt to unseat Clinton from her present perch as the Democratic heir apparent to Barack Obama will not be forgotten. If Warren lunges at Clinton and misses, she can expect the remaining three years of her term to be especially frustrating. What’s more, as Frum suggests, Warren is unlikely to be able to retain her present status as progressive icon until 2020. Is that risk worth a presidential bid? Maybe not.