Mitt Romney held a high-dollar fundraiser Thursday night at the home of John Paulson, the controversial hedge-fund billionaire who made a fortune shorting the housing market and subprime mortgages in 2007.

New York grocery billionaire John Catsimatidis told The Daily Beast the fundraiser, at Paulson’s posh townhouse at 9 East 86th Street on the Upper East Side of Manhattan, was a “big-dollar event” for wealthy donors like himself “fighting for the soul of America.” The Romney campaign did not return requests for information about the fundraiser—which was not listed on the candidate’s public schedule. Paulson’s publicist, Armel Leslie, also did not return calls seeking comment.

A neighbor who witnessed the event from across the street described it to The Daily Beast as a large crowd of “older white people, mostly men,” who started showing up around 7:30 p.m. Thursday. Around 8 p.m., sirens started blaring as more and more people started to show. There was security at the door as well as a police car on the street.

Then things became quiet until the sirens started up at 9:30 p.m. An SUV tried to block 86th Street, but New York drivers characteristically went around it. Then, as the security stood in the street, Romney emerged from the townhouse, “looking tall and neat.” He took off his suit jacket and climbed into the SUV.

The event marks a rather controversial departure for the Romney campaign. Although both Romney and his super PAC have accepted donations from Paulson, this ratchets up the association between the presumptive GOP nominee and the controversial Wall Street billionaire. Lis Smith, a spokesman for the Obama campaign, did take advantage of the connection to take a whack at Romney, stating, “It’s not surprising that the people who profited the most from the economic crisis want to elect Mitt Romney. He would bring back the failed policies—tax cuts for the wealthiest Americans and letting Wall Street write its own rules—that created it in the first place.” Then again, Paulson is a nice checkbook to get to know in gearing up for a fierce battle this fall. According to the latest numbers from The Center for Responsive Politics, Romney has out-raised President Obama by a four to one margin among donors in hedge funds and private equity. Romney's campaign has raised $2.48 million in this industry while Obama has collected just under $625,000.

Until Election Day, Romney and Obama will each try to hang the unpopularity of Wall Street on the other—Obama, by attacking Romney as a “vulture capitalist,” just as Rick Perry and Romney will go after Obama on “bailouts.” It’s unclear whether this attack will stick to either one, but by holding a fundraiser at Paulson’s townhouse, Romney made it that much easier for Obama.