WASHINGTON — Hedge fund and private equity managers will get their chance today in public to urge lawmakers on Capitol Hill to reject a proposal to raise their taxes.

Leading industry representatives, including a managing director of the Carlyle Group, will testify before the Senate Finance Committee and are expected to warn the panel that higher taxes on profits could harm the economy and drive investment overseas.

Legislation is circulating in both the House and Senate that could more than double the tax rate for hedge funds and private equity firms that go public, along with the taxes their executives pay. The push has come amid increased scrutiny of the vast profits that the firms have earned, and as Democrats in Congress seek new sources of revenue.

The biggest name on the witness list of seven is Bruce Rosenblum of the Carlyle Group, who heads the industry’s recently formed trade association, Private Equity Council. A notable absence from the panel is the hedge fund manager who has garnered the most attention of late, Stephen Schwarzman of the Blackstone Group. A committee aide said last night that Blackstone had declined an invitation to send a representative and instead referred the committee to the Private Equity Council, of which it is a member.

Today’s hearing is the second the Finance Committee is holding this month on the topic of “carried interest,” a term that refers to the investment profits earned by fund managers. Carried interest is currently taxed at the capital gains rate of 15%, but a proposal by House Democrats would make the profits subject to the tax rate on individual income, meaning it could go as high as 35%.

A separate Senate bill would make a similar rate change to the corporate taxation of private equity firms that go public, such as Blackstone. The Democratic chairman of the Finance Committee, Senator Baucus of Montana, and its ranking Republican, Senator Grassley of Iowa, are backing that proposal.

The Private Equity Council opposes both bills, a spokesman, Robert Stewart, said yesterday.

“We believe that the current tax treatment is correct,” he said. “Given what private equity does, that it benefits literally tens of millions of Americans through enhanced returns to pension funds, and endowments and foundations, and that private equity investments strengthen companies around the country, we don’t believe that it makes sense to change the system.”

Mr. Stewart also cautioned that raising taxes could undermine American competitiveness and push private equity firms overseas. Some critics of that argument have called it an overstatement, questioning whether that impact is actually likely. Mr. Stewart said that while current industry leaders may not leave, a tax hike could affect the “next generation” of firms. “We’re not suggesting that Carlyle or Blackstone is going to pull up stakes and leave Washington or New York and go overseas,” he said. “But it doesn’t take much more than some smart men and women and some computers to set up a private equity firm, and clearly if the tax incentives are better overseas then that may well be where the economic activity occurs.”

Also scheduled to testify today is the president of DLC Management Corp., Adam Ifshin; a managing principal at Oaktree Capital Management LP, John Frank; and William Stanfill, a founder of Trailhead Partners LP.

The battle over hedge fund and private equity taxation faces a complex political landscape. The three leading Democratic candidates for president — Senator Clinton, Senator Obama, and John Edwards — have all endorsed the tax increase, but the party’s congressional leadership is in less of a hurry. The Senate majority leader, Harry Reid of Nevada, has said a vote will not be held before the end of the year, and the Bush administration has said it is opposed to the idea.

Supporters of the legislation also have a formidable foe in Senator Schumer, who sits on the Finance Committee and is the Senate’s third-ranking Democrat. While he backs tax increases on high earners he has indicated he will resist any effort to single out Wall Street, which is the state’s economic engine and a key source of his campaign contributions.

Still, the private equity industry views the push for higher taxes as more than a passing political fad.

“There is a genuine concern that if they don’t fight it, it will end up being the law,” a New York attorney with Jones Day who represents private equity firms, Robert Kennedy, said.