Fink has begun assisting Bush leadership PAC Right to Rise with its fundraising strategy, according to the sources, who requested anonymity because they were not authorized to discuss the appointment.
A Bush spokeswoman said no final staffing decisions have been made at the super PAC.
Should Bush move forward with a 2016 presidential campaign, Fink is expected to transition to the Right to Rise super PAC, which legally must operate independently of Bush's official campaign, but could raise unlimited funds to promote Bush's candidacy and attack his rivals. Fink would be the super PAC counterpart to Heather Larrison, who has been overseeing Bush's aggressive fundraising so far this year and is expected to be finance director on the official campaign.
Fink, 36, who now lives in California, is a former private equity analyst and has deep ties in the finance and investment worlds, as well as to the moneyed Mormon elite in the Mountain West. Fink has longstanding personal relationships with Romney loyalists, some of whom remain uncommitted in the 2016 presidential race.
Fink was part of the founding team of Solamere Capital, the Boston-based private equity firm started by Zwick and by Romney's eldest son, Tagg.
On Romney's 2012 campaign, Fink was the day-to-day manager of the finance operation while Zwick split his time between the campaign and Solamere. Inside Romney's Boston headquarters, Fink was highly regarded for skillfully cultivating relationships with major donors as well as for his political expertise and sense of humor.
Zwick has not backed a candidate in 2016, but has said complimentary things about Sen. Marco Rubio (R-Fla.) as well as Bush. Romney, Zwick and other Romney intimates have warmed towards Rubio, although many of Romney's biggest fundraisers have signed on with Bush.