Private and corporate donors will contribute an estimated $67.2 million to fund next week's Democratic National Convention, putting it "on track to be the most expensive Democratic convention ever in terms of private fundraising," according to a report from a public interest group scheduled to be released Friday morning.

"The convention offers another outlet for spending by mega-donors and corporations interested in influencing political outcomes," said the report from the U.S. Public Interest Research Group. The Washington-based advocacy group believes that convention and campaign donations from large corporations and wealthy individuals give them too much influence on government policies.

"It earns them a seat at the table that your average American voter doesn't have," said Chris MacKenzie, communications and digital director for the group.

Convention funding comes from several sources. A city host committee raises the lion's share, with the idea being that a political convention is an economic development initiative for the region's businesses.

The party also kicks in some money.

Philadelphia Host Committee spokeswoman Anna Adams-Sarthou said the committee would have no comment on the report. There was no immediate response from the Democratic National Convention Committee.

Besides the city and the party, the federal government has also provided convention funding in two buckets, one for general expenses and another for security.

This year marks the first convention cycle in which the federal government is not providing any general funding, although both cities received the usual $50 million for security.

It is also the first year that donors have been allowed to give up to $100,200 to underwrite conventions - triple what was allowed in the past, the report said.

The 2012 Democratic convention in Charlotte cost $75.74 million, the report said, basing its analysis on Federal Election Commission reports.

Of that, $18.2 million was federally funded.

The rest, $57.53 million came from private donors, either via Charlotte's host committee or through the city's host committee or New American City, a group formed when Charlotte's fundraising fell short.

In 2012, major donors to the Democratic National Convention included Duke Energy, Bank of America, Dreamworks II Financial, and AT&T - all of which gave more than $1 million each.

In Philadelphia, the host committee pledged to raise $60 million, but had fallen short as of late last week. As of July 14, the host committee had $55 million in cash and confirmed commitments, and about $16 million in in-kind contributions, Adams-Sarthou said.

The host committee said it will not report its donor list and expenses until the deadline set by the Federal Election Commission - 60 days after the event ends July 28.