Sen. Blanche Lincoln (D-Ark.) has backed out of a plan to host a big-dollar charity concert for elite donors at this summer’s Democratic National Convention, shortly after coming under fire from an unlikely source — a liberal watchdog group that has until now focused its attacks on Republicans.

Citizens for Responsibility and Ethics in Washington — a nonprofit headed by former federal prosecutor and Democratic Hill aide Melanie Sloan — filed a complaint about Lincoln’s concert with the Senate Ethics Committee on Tuesday.

In addition to targeting the Lincoln concert, CREW also asked the panel to examine a plan by Majority Leader Bill Frist (R-Tenn.) to host an event during the Republican National Convention in New York that would benefit a number of AIDS groups.

Late Tuesday, however, Lincoln issued a statement that said she “regretfully” was withdrawing her name from association with the convention event, though “not because I believe it is wrong for Members of Congress to help charities like CureSearch in this way.”

Lincoln said she was “confident that my role in this event is permissible under Senate Ethics Rules, as is my role in similar non-profit fundraising events for which I have served as honorary chair in Washington and in my home state of Arkansas for many years.”

Earlier in the day, Sloan had attacked the notion of charity-based political fundraisers. “The use of charitable organizations — by both Democrats and Republicans — to finance convention events is a reprehensible misuse of charities, reflecting poorly on the Senate as well as the charities involved,” Sloan said.

CREW’s complaint asked the Ethics Committee to investigate the two matters and render an opinion that prohibits Senators from exploiting charitable organizations for political gain.

The planning of the charity events by Lincoln and Frist followed an outcry by some Democrats last year over House Majority Leader Tom DeLay’s (R-Texas) plan to raise money during the GOP convention for a tax-exempt group he is forming to benefit abused children.

Lincoln, one of six Senators on the evenly split Ethics Committee, had been planning to chair a concert during the July convention that would benefit CureSearch, a program of the National Childhood Cancer Foundation. The main sponsors of the event were to include AFLAC Inc., the Georgia-based insurance company, Atlanta energy giant the Southern Co., and several other Peach State firms.

The most expensive donor packages for the July 28 Democratic concert, called “Rockin’ on the Dock of the Bay,” were set at $100,000 for corporations, trade associations and individuals. The late-night concert at The Roxy nightclub was designed to honor seven Southern Democratic Senators including John Breaux (La.), John Edwards (N.C.), Bob Graham (Fla.), Fritz Hollings (S.C.)., Mary Landrieu (La.), Bill Nelson (Fla.) and Mark Pryor (Ark.).

According to a brochure for the Democratic concert, a $100,000 donation — known as a “Bay Access Pass” — will provide eight backstage passes and a photo op “with major talent,” plus 25 VIP lounge passes that offer “private balcony access, premium bar, seated viewing, and personal wait staff.” The package also includes 100 general admission tickets and “headliner visibility in promotional materials and event signage.”

Other donor packages include the “Inner Harbor Pass” ($50,000), the “Channel Pass” ($25,000), the “River Pass” ($10,000), the “Pier Pass” ($5,000) and the “Dock Pass” ($2,500).

The brochure also includes a disclaimer stating: “Rockin’ on the Dock of the Bay is a private, invitation-only event not connected with or sanctioned by the Democratic National Party or any official committee of the 2004 National Party Convention.”

A similar event chaired by Sen. Saxby Chambliss (R-Ga.) is scheduled in August during the GOP convention. CREW has not yet challenged the Chambliss event because they were unaware of it until Tuesday.

Frist’s event is a concert and reception to benefit several AIDS charities at Rockefeller Center during the GOP festivities. The event is seeking donations up to $250,000.

Under federal campaign finance law, Senators and Members may not raise or solicit soft-money contributions, although they may be “honored” at such events.

The mushrooming number of charitable events scheduled for this year’s conventions has also caused a philanthropic watchdog group to call for the Ethics Committee to outright ban lawmakers from participating in charitable events during the conventions because the association with politicians is bad for charities.

“We think it shouldn’t happen,” said Rick Cohen, executive director of the National Committee for Responsive Philanthropy. “When charities are either used or misused by politicians and donors are essentially buying face time and influence with lawmakers, it actually harms charities. While it may be good in the short term for the individual charity, the potential for political abuse will come back to hurt charities.”

Laura Kane, a spokeswoman for AFLAC, said she could not comment on the ethics complaint. But she noted that the names of all contributors to the charitable concerts in Boston and New York will be disclosed.

“We will disclose everything,” Kane said, adding that the company reviewed all of its plans with tax law experts who said the fundraisers complied with all applicable laws and rules.

DeLay’s charity, which is still awaiting formal recognition from the IRS, does not plan to reveal its donors. Tax law generally protects charities from publicly revealing contributors.

Sloan argued that the convention charities are simply a way for lawmakers to evade the ban on soft-money contributions implemented by the Bipartisan Campaign Reform Act. She predicted that most of the donors giving money will be lobbyists and corporate representatives seeking legislative favors from Congress.

She pointed out that the charitable groups will receive money only if there are funds left after paying off the cost of mounting the concerts.

She also contended that the public image of charities following a number of scandals within the nonprofit world will not be enhanced with connections to politicians.

While backing out of the convention event, Lincoln said she has “contacted representatives of AFLAC and CureSearch and indicated my interest in serving in this same capacity for a fundraising event in Washington at some other time.”

While Common Cause and Democracy 21 have repeatedly sought action by the House Committee on Standards of Official Conduct against DeLay’s charity, neither organization has filed a complaint over the Democratic plans.

Section 3(b) of the Senate Gift Rule prohibits a gift of a charitable contribution made by a registered lobbyist or an agent of a foreign principal on the basis of a designation, recommendation, or other specification of a Member, officer or employee. The rule provides an exception for mass mailing or other solicitations directed to a broad category of persons or entities.

Sloan also noted that federal tax law and the IRS broadly prohibit tax-exempt groups known as 501(c)(3)s from intervening in political campaigns.