Continuing her efforts to play an increased role in the shaping of the Democratic Party’s message, Sen. Hillary Rodham Clinton (N.Y.) has become deeply involved in assembling and raising money for a new outside organization designed to provide a voice to the party’s progressive wing. Although the finishing touches are still being put on the group, it is expected to be either a 501(c)3 or 501(c)4 group aimed at “countering the efforts by the right in terms of research and policy development as well as communications outreach,” according to one source familiar with its genesis.

Both potential vehicles, referred to by their designation in the Internal Revenue Service, offer pros and cons.

A 501(c)3 is a charitable organization largely banned from engaging in political activity. Donations are tax-exempt and do not have to be disclosed.

A 501(c)4 is allowed to dabble in political activity although contributions to it are not tax-deductible. The group still does not have to disclose its donors.

There is a distinct possibility that both a 501(c)3 and a 501(c)4 committee will be established, with the former functioning as a Democratic think tank and the latter as a rapid research and response communications outlet, said one observer.

The creation of the committee — or committees — comes as Democrats are seeking a more unified message to counter President Bush, who was an effective messenger for the GOP in the 2002 elections when Republicans retook control of the Senate and gained six House seats.

One Democratic strategist described Clinton, who is widely believed to be eyeing a presidential bid as early as 2008, as “the tinder to the flame” for the new operation.

“Hillary is getting power because she can put the money in,” added the strategist. “You need the money in the bank.”

People familiar with the new organization say Clinton’s role remains largely undefined, but as an icon to the more liberal wing of the Democratic Party, she is likely to play a significant part in its operations.

“This is not a Hillary thing per se, but she will be very involved,” said a source familiar with the group, who noted that a number of other Democratic Senators are also likely to play a role in the organization. Several Senators interviewed Tuesday said they were unaware of the development of such a committee.

For her part, Clinton declined to address specific efforts on behalf of the new organization, saying only: “I am encouraging anybody to do whatever they can to have a strong, positive, and effective Democratic message.”

In addition to Clinton, a number of former aides to her husband during his eight years in the White House are also expected to play roles.

Former White House Chief of Staff John Podesta has been spearheading the effort while former Clinton Press Secretary Joe Lockhart and political office director Doug Sosnik are also expected to assist with the new organization. Mike Lux, another former Clinton political operative, and now president of Progressive Strategies LLC, is also involved.

Neither Podesta nor Lux returned calls for comment.

Sources said Laura Nichols, former communications director for Rep. Richard Gephardt (Mo.), has been approached to head the group.

Nichols is now at the Corporation for Public Broadcasting and had previously been expected to join Gephardt’s presidential campaign.

The revelation of Clinton’s involvement comes on the heels of her appointment to head the Steering and Policy Committee, a mid-level leadership position charged with articulating the party’s message through the media and strengthening ties with outside interest groups.

Clinton has sent word to Democratic aides that one of her first directives as head of the committee will be to establish a speakers bureau, designed to offer media outlets one-stop shopping as they look for guests to address key issues.

The speakers bureau will maintain a database of local and national elected officials, as well as academics and other members of the Democratic political intelligentsia willing to speak on issues of the day.

Since her election in 2000, Clinton has rapidly ascended the Senate ranks, emerging as one of the top fundraisers within her Caucus.

Her leadership PAC — HILLPAC — has become one of the most generous funders of both House and Senate candidates.

In the 2002 cycle, Clinton raised $3.2 million through the PAC and doled out contributions to 25 Senate candidates and 86 House candidates.

During her open-seat race against then-Rep. Rick Lazio (R), Clinton spent better than $41 million to win a convincing 55 percent to 43 percent victory.

The structure of the new organization is expected to somewhat mirror that of Lux’s firm, which advises wealthy donors and interest groups about how to put their money to its best use in the political process.

In the 2002 cycle, Lux helped form the Progressive Donor Network, which was comprised of several hundred contributors, and sought to connect them to like-minded groups.

The vision for the new group is to “take what Lux has done and do it bigger and better,” said one Senate leadership aide.

Ed Henry contributed to this report.