WASHINGTON • Sen. Kyrsten Sinema, the Arizona Democrat who single-handedly thwarted her party’s longtime goal of raising taxes on wealthy investors, received nearly $1 million over the past year from private equity professionals, hedge fund managers and venture capitalists whose taxes would have increased under the plan.

For years, Democrats have promised to raise taxes on such investors, who pay a significantly lower rate on their earnings than ordinary workers. But just as they closed in on that goal last week, Sinema forced a series of changes to her party’s $740 billion election-year spending package, eliminating a proposed “carried interest” tax increase on private equity earnings while securing a $35 billion exemption that will spare much of the industry from a separate tax increase other huge corporations now have to pay.

The bill, with Sinema’s alterations intact, was given final approval by Congress on Friday and is expected to be signed by President Joe Biden this week.

Sinema has long aligned herself with the interests of private equity, hedge funds and venture capital, helping her net at least $1.5 million in campaign contributions since she was elected to the House a decade ago. But the $983,000 she has collected since last summer more than doubled what the industry donated to her during her preceding years in Congress combined, according to an Associated Press review of campaign finance disclosures.

The donations, which make Sinema one of the industry’s top beneficiaries in Congress, serve a reminder of the way that high-power lobbying campaigns can have dramatic implications for the way legislation is crafted, particularly in the evenly divided Senate where there are no Democratic votes to spare. They also highlight a degree of political risk for Sinema, whose unapologetic defense of the industry’s favorable tax treatment is viewed by many in her party as indefensible.

“From their vantage point, it’s a million dollars very well spent,” said Dean Baker, a senior economist at the Center for Economic and Policy Research, a liberal-leaning think tank.

“It’s pretty rare you see this direct of a return on your investment. So, I guess I would congratulate them.”

Hannah Hurley, a Sinema spokesperson, acknowledged the senator shares some of the industry’s views on taxation, but rebuffed any suggestion that the donations influenced her thinking.

“Sen. Sinema makes every decision based on one criteria: what’s best for Arizona,” Hurley said in a statement. “She has been clear and consistent for over a year that she will only support tax reforms and revenue options that support Arizona’s economic growth and competitiveness.”

The American Investment Council, a trade group that lobbies on behalf of private equity, also defended their push to defeat the tax provisions.

“Our team worked to ensure that members of Congress from both sides of the aisle understand how private equity directly employs workers and supports small businesses throughout their communities,” Drew Maloney, the organization’s CEO and president, said in a statement.

Sinema’s defense of wealthy investors’ tax treatment offers a jarring contrast to her background as a Green Party activist and self-styled “Prada socialist” who once likened accepting campaign cash to “bribery” and later called for “big corporations & the rich to pay their fair share” before launching her first campaign for Congress in 2012.

She’s been far more magnanimous since, praising private equity in 2016 from the House floor for providing “billions of dollars each year to Main Street businesses.” After her election to the Senate, Sinema interned during the 2020 congressional recess at a private equity mogul’s boutique winery in northern California.

The soaring contributions from the industry to Sinema trace back to last summer. That’s when she first made clear that she wouldn’t support a carried interest tax increase, as well as other corporate and business tax hikes included in an earlier iteration of Biden’s agenda.

During a two-week period in September alone, Sinema collected $47,100 in contributions from 16 high-ranking officials from the private equity firm Welsh, Carson, Anderson & Stowe, records show.