U.S. Senator Kyrsten Sinema (D-AZ) waits for an elevator to go to the Senate floor at the U.S. Capitol in Washington, U.S. August 2, 2022.  REUTERS/Jonathan ErnstU.S. Senator Kyrsten Sinema (D-AZ) waits for an elevator to go to the Senate floor at the U.S. Capitol in Washington, U.S. August 2, 2022. 

Those working at Wall were the ones who held up a massive spending bill that promised to create jobs, invest in clean energy and tax the wealthy.

The carried interest tax provision would have closed an arcane loophole in tax law that allowed hedge fund managers, law firm partners and private equity executives to pay less taxes than ordinary workers.

It was supposed to help pay for $433 billion in climate and health initiatives by closing that loophole.

Senate Majority Leader Chuck Schumer said Democrats had no choice but to remove that provision from the Inflation Reduction Act in order to get Sinema's vote. The Senate voted 51-50 on Sunday to approve the massive spending-and-tax package. The House is expected to approve it this week.

The head of the trade group representing the world's largest private equity firms began cranking up the pressure on Sinema and fellow Arizona Sen. Mark Kelly, who is also a Democrat.

Drew Maloney, the president and CEO of the American Investment Council, wrote in an op-ed published by an Arizona news outlet that the upcoming infrastructure debate would be critical to the future of Arizona. Some of the world's largest private equity firms are represented by the group. He urged them to support private investment in helping small businesses.

Retaining carried interest capital gains and preventing elimination of interest deductibility is one of the group's top priorities.

"Our team worked to ensure that members of Congress from both sides of the aisle understood how private equity directly employs workers and supports small businesses throughout their communities." We helped prevent tax increases that would make it harder for investors to support jobs and small businesses in every state.

Last year, Sinema told Democratic leaders she opposed closing the carried interest tax break. It was removed from a House bill.

The bill was significantly scaled back to win over the two moderate Democrats who were opposed to it.

Senator Sinema makes decisions based on what's best for Arizona, according to her spokeswoman. She said that Sinema will only support tax reforms and revenue options that support Arizona's economic growth and competitiveness. Sinema thinks that incentives to invest in Arizona businesses would hurt the state's economy and ability to create jobs.

According to people familiar with the matter, lobbyists for hedge funds, private equity firms and other money managers called Sinema's office in the weeks leading up to the vote. The senator and her staff held a lot of in-person meetings with the industry in the run up to the deal.

Sinema has been sympathetic to the industry since she became a senator. She met Michael Forman, the CEO of a Philadelphia-based investment firm, and one of his executives at a restaurant in Philadelphia last September. Forman didn't reply to calls or emails.

A lobbyist representing some of the biggest investment firms in the world told CNBC that Sinema was meeting with every major industry that was not in favor of the bill. Sinema said she would work on her own.

As a member of the House of Representatives, Sinema supported private equity investments. According to the New York Times, Sinema said the industry gave Billions of dollars to Main Street businesses.

Sinema won a seat on the powerful Banking Committee and immediately began raising money for the industry she would oversee. According to Federal Election Commission data analyzed by the nonpartisan campaign finance watchdog Open, she has raised at least $2 million from the securities and investment industry since the beginning of the election cycle. Both Sinema and Brown are running for reelection in four years.

Half of the American Investment Council's political action committee donations went to Sinema's campaign.

According to campaign finance data, employees at private equity firms gave more than $95,000 to Sinema in the last election and will give more in the next one.

There were donations from KKR co-founders Henry Kravis and George Roberts. The political action committees of Carlyle and Apollo gave a combined $15,000 to Sinema.

Representatives for KKR and Carlyle didn't want to say anything. Representatives for the two companies didn't return calls.

The carried interest loophole is one of the reasons why some of Wall Street's wealthiest money managers want to keep it. Instead of paying the standard individual income tax rates of up to 37% for individuals who earn more than $500,000 a year, carried interest is taxed at the capital gains rate, which is usually 20% for high-income earners.

Executives were supposed to hold those investments for at least five years in order to get a better rate. The industry says carried interest tax breaks help small businesses. Critics say it is a huge tax break for the wealthy.

The private equity industry was praised by Lloyd Blankfein after the carried interest provision was removed from the inflation reduction act. The highest paid people still pay the lower capital gains tax on their earnings.