Sen. Joseph Biden (D-Del.) is reversing two decades of his own personal prohibition against PAC money today as he takes his first major financial step toward running for the White House.

Biden, who hasn’t accepted donations from political action committees for his re-election campaigns since the mid-1980s, is asking for a minimum $2,000 contribution from PACs to be considered a “friend” of Unite Our States. That’s the name of the leadership PAC that Biden officially launches this evening at a private fundraiser, a six-figure gala hosted by 20 lobbyists, former lawmakers and Democratic fundraisers.

Biden aides stressed that the decision to take PAC money for Unite Our States is consistent with the Senator’s views. “Sen. Biden did receive PAC money for a couple of his re-elections, but then decided he didn’t need to raise PAC money,” said Danny O’Brien, Biden’s chief of staff.

Biden’s decision, while sure to be criticized by both those pushing to see less money in politics and his GOP antagonists, is a tacit recognition that PACs are no longer considered the political boogeymen that they once were.

Also, while no one in Biden’s camp will say so publicly, it’s an acknowledgement that Biden will need to raise every dollar possible for a process expected to be dominated by Sen. Hillary Rodham Clinton (D-N.Y.) and her massive fundraising capabilities.

Unite Our States and the other leadership PACs — such as Clinton’s Hill PAC and Sen. John Kerry’s (D-Mass.) Keeping America’s Promise — cannot be used to directly support a presidential campaign. But the PAC will enable Biden to start spreading money around to critical players in key states such as Iowa, New Hampshire and South Carolina, which were home to the first three big fights in the 2004 primary campaign.

It will also help pay for his political travels, something he has stepped up in recent months by headlining Jefferson-Jackson dinners for state party committees in places like South Carolina and Florida.

Until registering Unite Our States with the Federal Election Commission on June 29, Biden had not had a PAC in about 20 years.

In accepting contributions from other PACs, he is following a trail blazed for him four years ago by Kerry, who, like Biden, used to foreswear campaign donations from PACs. But during the earliest stages of his White House bid in 2001, Kerry launched a PAC and began taking in cash from other PACs and suffered no noticeable political fallout for changing his stance on the special-interest cash.

It’s unclear if Biden would accept PAC cash for a presidential bid.

As expected, a key financial player in Biden’s PAC is Joe Cari, a Chicago-based fundraiser who was with Biden in his maiden campaign for president in 1987 and who went on to become finance chairman of the Democratic National Committee. Biden was in Chicago over the weekend in meetings with Cari and other Windy City political operatives, according to the Chicago Sun-Times.

While far from matching the lengthy list of institutional players on Clinton’s unofficial political team, Biden has assembled a group of 20 co-hosts for his kickoff event for Unite Our States — each of whom had to donate or raise at least $5,000 for the evening.

The list includes former Rep. Marty Russo (D-Ill.), who is now president of Cassidy and Associates and one of the most prominent Democratic lobbyists in town. Former Michigan Gov. James Blanchard (D) is also a co-host, as is Bill Oldaker, a prominent Democratic lawyer whose partner is Biden’s son, Hunter.

Rita Lewis, a former aide to the Democratic Senatorial Campaign Committee and the Clinton White House, is also a co-host.

The reception is being hosted in the Georgetown home of Frank Loy, the undersecretary of state for global affairs in the State Department when Madeleine Albright was the nation’s top ambassador. “The more successful he is at this, the more successful Sen. Biden could be in the presidential race,” O’Brien said.

A bit of a long shot for the nomination, Biden is already playing catchup with his potential competitors for the 2008 nod. Kerry’s Keeping America’s Promise PAC was up and running six months ago and dished out $22,000 in donations in the first quarter.

In addition, Kerry’s PAC is paying the salary of one aide to the New Hampshire Democratic Party, as is former Sen. John Edwards (D-N.C.) through his One America PAC.

Clinton’s Hill PAC has been operating since early 2001. In the first six months of 2005, Hill PAC raised more than $715,000 and donated $75,000 to federal candidates and party committees.