Organizers from eight liberal groups that have a total membership of nine million Americans asked for Clinton to clarify whether she "continues to support 'golden parachute' bonuses for Wall Street executives who take government positions or whether she will join others in the Democratic field in opposing them."
The letter, send via email to campaign aides but marked for Clinton, asks Clinton whether she supports Sen. Tammy Baldwin and Rep. Elijah Cummings' "Financial Services Conflict Interest Act," a bill that would
prevent "government employees from accepting bonuses from their former private sector employers for entering government service."
"Two of your opponents -- Sen. Sanders and Gov. O'Malley -- have announced support" for the act, the letter reads. "To date, however, you have not articulated a position on this bill or on the larger question."
O'Malley endorsed the legislation shortly after it was announced and Sanders is a co-sponsor.
The letter continues by asking two questions: "Do you still support the use of this controversial compensation practice?" and "If you become President, will you allow officials who enter your administration to receive this sort of bonus?"
Clinton campaign aides did not respond to requests for comment and questions from CNN.
One reason the left is coalescing around the revolving door between Washington and Wall Street: Sen. Elizabeth Warren
At this year's Netroots Nation, a conference that brings most of the nation's liberal organizations together, Warren called on all 2016 candidates to curb the influence of Wall Street within their campaigns.
"Anyone who wants to be president should appoint only people who have already demonstrated they are independent, who have already demonstrated that they can hold giant banks accountable, who have already demonstrated that they embrace the kind of ambitious economic policies that we need to rebuild opportunity and a strong middle class in this country," Warren said.
Warren added that Baldwin and Cummings' plan was "a bill any presidential candidate should be able to cheer for."
The letter argues that Clinton has tacitly supported the payouts in the past, noting two aides at Clinton's State Department reportedly received benefits upon leaving their jobs to the government.