Newt Gingrich, whose allies have spent millions of dollars on advertisements painting Mr. Romney as a heartless “vulture capitalist,” seized on Mr. Romney’s Goldman ties at Thursday’s Republican debate in Florida, suggesting that he had profited through Goldman on banks that had foreclosed on Floridians. And as the fight over regulation of financial firms spills onto the campaign trail, Mr. Romney’s support for the industry — he has called for repeal of the Dodd-Frank legislation tightening oversight of Wall Street — may draw more fire.

Mr. Romney’s positions and pedigree have helped draw to his side major donors in the financial world. The securities and investment industry has given more money to Mr. Romney than any other industry, according to the Center for Responsive Politics, and some of its leading figures have donated millions of dollars to Restore Our Future, the “super PAC” bolstering Mr. Romney’s campaign. Goldman employees are also the biggest source of donations to Free & Strong America PAC, a group Mr. Romney founded but no longer controls.

But Mr. Romney’s personal finances are particularly entwined with Goldman.

His federal financial disclosure statements show Mr. Romney and his wife, their blind trusts and their family foundation to be prodigious consumers of the bank’s services. In 2011, Mr. Romney’s blind trust and the couple’s retirement accounts held as much as $36.7 million in at least two dozen Goldman investment vehicles, earning as much as $3 million a year in income. Mrs. Romney’s trust had at least $10.2 million in Goldman funds — possibly much more — earning as much as $6.2 million.

Tax returns released by the campaign this week also highlighted some of the privileges Mr. Romney enjoyed as a friend of Goldman: In May 1999, a few months after he left Bain to run the Salt Lake City Olympics, Goldman allowed Mr. Romney to buy at least 7,000 Goldman shares during the firm’s lucrative initial public offering — a generous allotment even among Goldman clients, according to people with knowledge of the deal. When Mr. Romney’s trusts sold the shares in December 2010, a few months before he formed his presidential exploratory committee for the 2012 race, they returned a profit of $750,000.

A spokeswoman for Goldman declined to comment, as did a spokeswoman for Mr. Romney.

Investing with Goldman was not without risks: Like other Goldman clients, the Romneys invested money in a family of funds known as Whitehall, which placed highly leveraged bets on office buildings, casinos and hotels. Some Whitehall deals collapsed during the financial crisis, saddling Mr. Romney and its other investors with big losses.