With Jeb Bush’s departure Saturday from the Republican presidential race, Marco Rubio is now the sole remaining candidate (excepting John Kasich) among the so-called establishment lane. The result should be a major infusion of money for his cash-strapped campaign, as moderate-friendly donors prepare to step off the sidelines and back Rubio as the most palatable alternative to Donald Trump and Ted Cruz. But Rubio is running out of time. And, in a time of rising populist outrage, becoming the likely favorite of the Republican donor class carries risks of its own.

Despite the incessant boosterism surrounding his campaign, Rubio had only $5.1 million on hand at the end of January, according to the most recent F.E.C. filings, and his own super-PACs had, by the end of 2015, about $14 million, though that might be largely diminished by the past three primary races. Nevertheless, that money is dwarfed by Cruz, who has $13.6 million on hand and a still-robust super-PAC that initially raised $36 million, and Trump, a billionaire who is self-funding his campaign.

One thing Rubio does have going for him is Wall Street, which has backed his candidacy more than any other. Reuters reports that employees of major banks gave nearly $4 million to his campaign this cycle—twice as much as his nearest rival for Wall Street’s favor, Jeb Bush, before he suspended his campaign. With Bush out and Kasich still an afterthought, more funding from the financial sector could be headed his way. But in a primary where Trump and Cruz have villainized, however hypocritically, the influence of corporate money on politics, that money could also be its own liability. Bush’s slow spiraling was aided in part by the existence of the cash hoarded by his super-PAC, Right to Rise, which provided Trump with a potent talking point to rip Bush during debates. (Incidentally, by the time he dropped out, Bush’s super-PAC only had an estimated $2.5 million left out of the $118 million it had raised.)

One potential solution, should Rubio find himself the recipient of a wave of donor largesse, would be to use the money to run ads against Trump himself, a tactic that few candidates have taken thus far. According to The New York Times, only 4 percent of the $215 million spent by super-PACs during this election went toward ads attacking Donald Trump, even as his popularity swelled. Such a move would be a huge gamble for Rubio—most of Trump’s supporters say Cruz is their preferred second-choice candidate—but it would also establish him as the one candidate willing to take on the front-runner.

In order for that or any strategy to work, however, Rubio first has to prove that he can do more than place a distance second behind Trump. More money from the donor class could help. Then again, all the campaign contributions in the world couldn’t save Jeb Bush. Becoming the avatar of the status quo may keep Rubio afloat for now, but running as the favorite of the Republican establishment comes with its own dangers, too.