Once regarded warily by much of the Democratic establishment, the liberal grass-roots group MoveOn.org is being increasingly courted by Democratic officeholders for its 3 million members — and their deep pockets.

The Web-based advocacy organization, by far the left’s most potent fundraising operation outside of the Democratic Party itself, has raised its profile considerably on Capitol Hill in recent months.

“It’s been an interesting experience for us,” said Eli Pariser, the executive director of MoveOn.org’s political action committee. “I don’t know to what degree it’s a political move and to what degree Democrats understand now it is important to court our constituency.”

Republicans have pounced on the increased cooperation, seeking to paint Democrats as beholden to their party’s liberal wing.

The National Republican Senatorial Committee recently released a six-page research document titled “How Much is that Donkey in the Window,” filled with positive comments made by Democratic leaders regarding MoveOn and highlighting the group’s issue positions.

Most controversial among them are the organization’s opposition to the use of force in Afghanistan following the Sept. 11, 2001, terrorist attacks, and to the war in Iraq.

“The Democrat Party at an unprecedented level has become best friends with MoveOn.org,” said NRSC spokesman Brian Nick. “On the major issues, we are [seeing] MoveOn.org is moving in lock step” with the Democratic Party, he added.

The most high-profile event illustrating the new synergy between MoveOn and Democrats came March 16 with a rally on Capitol Hill.

It drew Senate Minority Leader Harry Reid (Nev.) and Senate Minority Whip Dick Durbin (Ill.) as well as Sens. Charles Schumer (N.Y.), Robert Byrd (W.Va.), Edward Kennedy (Mass.) and Barbara Boxer (Calif.).

MoveOn followed that event with an e-mailed fundraising plea on Byrd’s behalf from Illinois Sen. Barack Obama (D). The message raised more than $800,000 for the West Virginia Senator in just 72 hours.

(Last October, Obama wrote two fundraising e-mails for MoveOn that netted $1.2 million for seven Senate candidates around the country.)

Behind the scenes, the organization has gained considerable entree as well.

House Minority Leader Nancy Pelosi (Calif.) has worked with MoveOn since being elected the top Democrat in the House leadership in late 2002, but the relationship between the two grew closer during the fight over adding a prescription drug benefit to Medicare, said spokeswoman Jennifer Crider.

Crider added that Pelosi or her staff have calls and meetings “on a weekly basis” with representatives of MoveOn.

The Senate Steering and Outreach Committee holds a Monday telephone call with roughly 20 outside advocacy organizations whenever Congress is in session. MoveOn has been a participant, though infrequently, sources said.

Susan McCue, Reid’s chief of staff, said that MoveOn “effectively represents an important part of our constituency.”

Laura Gross, a spokeswoman for the Democratic National Committee, also praised MoveOn’s efforts.

“Obviously they are relaying the Democratic Party message, which is in line with what the DNC is doing and what the Hill is doing as well,” said Gross.

She added that DNC Chairman Howard Dean participated in a March 10 conference call with members of the MoveOn PAC.

Pariser said that while MoveOn’s interests have paralleled those of the Democratic Party of late, that will not always be the case.

“We are not the party, and on issues where we diverge from some in the party we are going to” make it clear, Pariser promised.

On Monday, for example, MoveOn sent an e-mail designed to raise money for radio ads hitting House Members who support the stiffening of bankruptcy regulations — a bill that will be voted on this week.

Its most recent effort notwithstanding, Pariser acknowledged that MoveOn’s members recognize that “we are at a time when the Democrats are the only thing standing between Republicans and disaster” on such issues as Social Security and judicial nominations.

In recent weeks, MoveOn has aired ads on both issues in targeted districts and on national cable.

That connection has not gone unnoticed by Republicans who believe that MoveOn’s donations to Democrats — estimated to be in the hundreds of millions of dollars — during the 2004 cycle bought them a seat at the table with the party.

Nick and Republican National Committee Deputy Communications Director Tracey Schmitt made reference to an e-mail to MoveOn members sent earlier this year by Pariser, in which he wrote: “Now it’s our party: We bought it, we own it and we’re going to take it back.”

Schmitt said such a statement “should trouble the party.”

“After spending millions of dollars to defeat President Bush, they are now going after his agenda,” Schmitt added. “They are completely out of touch with mainstream America.”

Pariser dismissed such criticisms as a sign of Republicans’ anxiety over his organization’s activities.

“Republicans are trying very consistently to wedge between this big group of middle-class Americans and the Democratic leadership,” he said. “It’s not working because the charge is baseless.”

Privately, Democratic insiders admit that publicly associating with MoveOn does carry potential pitfalls for the party, but they argue that the money and grass-roots energy the group can deliver make such risks worthwhile.

Among elected Democratic leaders, there is a “recognition that MoveOn can excite the troops and till the ground to grow more Democratic activists in a way that makes any risks associated with their activities or their views less important than the rewards we can gain,” one party strategist said.

MoveOn “can be embraced when they need to be embraced and you can distance yourself from them when you need to,” the source added.