Yesterday, Newark, New Jersey Mayor Cory Booker (D) attacked the Obama campaign for making an issue of Mitt Romney’s tenure at Bain Capital during an appearance on Meet the Press. While the progressive leader later backed off the criticisms, Republicans have been quick to highlight his comments as an attack against the idea that scrutiny of Mitt Romney’s record as a businessman is fair game.

A ThinkProgress examination of New Jersey campaign finance records for Booker’s first run for Mayor — back in 2002 — suggests a possible reason for his unease with attacks on Bain Capital and venture capital. They were among his earliest and most generous backers.

Contributions to his 2002 campaign from venture capitalists, investors, and big Wall Street bankers brought him more than $115,000 for his 2002 campaign. Among those contributing to his campaign were John Connaughton ($2,000), Steve Pagliuca ($2,200), Jonathan Lavine ($1,000) — all of Bain Capital. While the forms are not totally clear, it appears the campaign raised less than $800,000 total, making this a significant percentage.

He and his slate also jointly raised funds for the “Booker Team for Newark” joint committee. They received more than $450,000 for the 2002 campaign from the sector — including a pair of $15,400 contributions from Bain Capital Managing Directors Joshua Bekenstein and Mark Nunnelly. It appears that for the initial campaign and runoff, the slate raised less than $4 million — again making this a sizable chunk.

In all — just in his first Mayoral run — Booker’s committees received more than $565,000 from the people he was defending. At least $36,000 of that came from folks at Romney’s old firm.

Cory Booker, the popular and progressive mayor of Newark, New Jersey, attacked the Obama campaign for making an issue of Mitt Romney’s tenure at Bain Capital during an appearance today on Meet the Press.

Romney has placed his career at Bain the center of his campaign. On several occassions Romney has asserted that, while at Bain, he was responsible for creating 100,000 jobs. Multiple independent fact checkers have concluded that Romney’s claims on jobs is simply false.

The Obama campaign has responded by highlighting instances where Romney’s actions at Bain Capital resulted in substantial job loses. On Meet the Press, Booker called criticizing Romney’s time at Bain “ridiculous” and “nauseating.” He also equated criticisms of Romney’s buisness record with racially charged attacks against Obama centered around Rev. Jeremiah Wright. Watch it:

At Salon, Steve Koracki speculates that Booker defended private equity to help cultivate Wall Street donors for a future state-wide race. Many of these donors have abandoned Obama, hoping for gentler treatment from a President Romney.

By this afternoon, Booker had started to walk back his criticisms of Obama and his campaign. Here’s what he said in a video posted to YouTube late today:

Mitt Romney has made his buisness record a center piece of his campaign. He’s talked about himself as a job creator. Therefore it is reasonable, and in fact I encourage it, for the Obama campaign to examine that record and to discuss it. I have no problem with that. I believe, in many ways, Mitt Romney is not being honest about his role and his record even as a business person and is shaping it to serve his political purposes and not necessarily including all the facts from his time there.

This clarification, however, is unlikely to find its way into the RNC press release touting Booker’s initial remarks.