Since the Democratic National Convention, Hillary Clinton has maintained a lead in most polls over her rival Donald Trump, prompting pundits to predict a Democratic win. Unworried by Trump, Clinton loyalists aren’t waiting for November to jockey for positions in the nominee’s hypothetical cabinet. But for many, a more serious specter looms over a potential Clinton administration: Elizabeth Warren, a progressive power player who is already flexing her muscles over crucial hiring decisions.

The popular Massachusetts senator has made herself invaluable to the Democratic Party, even as she has publicly undermined Clinton to advance her own agenda. Warren, who has endorsed Clinton, has been instrumental in closing the rift in the Democratic Party left by an acrimonious primary campaign against Bernie Sanders, stemming the flow of his supporters to Trump and bringing unity to the left. But now, as Clinton begins the final two-month sprint to Election Day, Warren appears to be seeking a return on her investment. A coalition associated with the senator is reportedly putting pressure on the Democratic nominee’s transition team to hire individuals who will help promote a progressive policy agenda from inside the Clinton administration, Politico reports—a requirement that could potentially exclude plenty of longtime Clinton allies.

The goal of Warren’s coalition, which is comprised of a number of liberal think tanks, progressive advocacy groups and individuals, is to curtail the influence if corporations and big banking institutions on the White House. “Our big point to the Clinton transition people will be that when it comes to positions with power over Wall Street, it is important to appoint people with a proven track record of challenging corporate power,” Adam Green, co-founder of the Progressive Change Campaign Committee, told Politico.

In Warren’s “hell no” category for appointees are corporate executives with ties to the industries they would be regulating, and individuals with strong ties to Wall Street, Politico reports. That would exclude Clinton friends like Robert Rubin, who held top positions at both Goldman Sachs and Citigroup before serving as treasury secretary for Bill Clinton, or __Michael Froman, __ who worked on Barack Obama's transition team while still on Citigroup's payroll. Instead, Warren reportedly hopes to line Clinton’s cabinet with a number of strong left-leaning liberal voices. And the senator’s efforts have already begun to pay off. The Democratic Party has reportedly adopted the Warren’s guideline that only those “who are not beholden to the industries they regulate” should receive appointments, Politico reports, and this week Clinton hired two Warren-approved progressives for her transition team, Heather Boushey and Rohit Chopra.

Warren’s bluster comes at a pivotal time in the Clinton campaign. As the Democratic nominee battles another deluge of controversy over her private e-mail server and fresh accusations that Clinton Foundation donors received preferential treatment during her State Department tenure, Clinton’s lead is beginning to look more precarious. Clinton is hoping to create a safe space for Republican defectors but needs to regain the trust of the electorate and can’t risk the appearance of reneging on the progressive promises she made to voters during and after the primary.

With Republicans expected to maintain control of the House, Clinton would likely be faced with a split Congress. Should she make it to the Oval Office, her executive branch would play a decisive role in legislation, as Obama’s did. It is not surprising then that Warren, who has proven to be a remarkably strategic operative during her first Senate term, has chosen to exert her political influence at a moment when she has maximum leverage.