Employees of the second-largest private equity firm, the Blackstone Group, made a big impact on presidential fundraising last month, showing up among the biggest sources of funds to both President Obama and Republican candidate Mitt Romney.

Private equity and its role in the economy have become one of the central themes in this year’s presidential contest, with Democrats attacking Mitt Romney’s record at the head of Bain Capital and Republicans pointing to it as an important source of experience.

Blackstone’s two top executives have chosen opposite sides in the race. Chief Executive Stephen Schwarzman is a major fundraiser for Romney, and his second in command, Hamilton “Tony” James, is a major bundler for Obama.

The company’s employees were the single biggest source of cash for Obama in May, giving $380,000 to his campaign and the Democratic National Committee.

Romney and the Republican National Committee received $361,000 from Blackstone employees in May, bested only by the $484,000 donated by employees of Elliott Management, the hedge fund company run by Romney bundler Paul Singer.

An Obama spokesman declined to comment. Romney’s campaign did not respond to a request for comment.

Blackstone spokesman Peter Rose declined to comment on the campaign contributions from Blackstone employees. He did confirm that the company hired Romney fundraiser Wayne Berman as its top lobbyist in Washington this week. Berman has raised $424,825 for Romney, according to federal disclosures.

The financial company was ranked as the second-largest private equity firm in 2012 by Private Equity International, with $49.6 billion in capital raised in the past five years.

Obama held a gilded fundraiser at James’s Manhattan home in mid-May, featuring gold-colored dining chairs and gold flowered tablecloths, surrounded by oil paintings in ornate gold frames, according to a pool report of the gathering.

“I believe the free market is the greatest wealth generator devised by man,” Obama said at the gathering. “Risk takers and innovators should be rewarded.”