Top Democrats on Capitol Hill, infuriated by AARP’s decision to endorse the GOP-crafted Medicare prescription drug bill on Monday, are accusing the influential seniors group of selling out older and disabled Americans and being “co-opted” by President Bush and the Congressional Republicans.

But officials at the 35 million-member AARP dismissed the Democratic attacks as inaccurate and needlessly partisan, and said the group is moving ahead with its plans to unleash a large-scale lobbying effort, including a multimillion-dollar TV and newspaper ad blitz worth $7 million.

“This is huge,” said Rep. Rob Portman (Ohio), chairman of the House GOP leadership. “For them to be willing to do some grassroots work is, I think, very significant.”

The AARP campaign is designed to convince wavering lawmakers to support the package, which would create a prescription drug benefit for 40 million Medicare recipients beginning in 2006.

What is not clear yet is the long-term fallout for either the Democrats or AARP from this split, which came despite the fact that AARP has long been more closely aligned with powerful Democrats like Sen. Edward Kennedy (Mass.) than GOP leaders like Speaker Dennis Hastert (R-Ill.).

“This is a big, big blow to Democrats,” said a top union official. “This really takes the wind out of their sails, although you could see this coming.”

AARP’s rupture with Democratic leaders left House Minority Leader Nancy Pelosi (D-Calif.) and Senate Minority Leader Tom Daschle (D-S.D.) scrambling to rally opposition to the proposal, expected to be voted on by both chambers later this week.

The AFL-CIO and other unions bitterly oppose the Medicare agreement, which would also establish a new role for private health plans within the Medicare program. Union insiders said that labor organizations will place tens of thousands of phone calls this week in an attempt to whip up opposition among seniors, as well as mass mailings, and a rally is planned for Wednesday to protest the bill. No decision has been made whether to try to match the AARP’s TV campaign yet.

But the efforts by organized labor and affiliated groups did little to mask the Democratic anger over AARP’s decision.

“I am deeply disappointed that AARP’s national leadership has been co-opted by Republicans pushing a partisan bill that fails to provide a real prescription drug benefit under Medicare and does not meet the principles AARP had insisted upon,” Pelosi said in a statement released by her office.

Pelosi added that the nation “cannot afford a Trojan horse deal, which purports to help America’s seniors, but is really a cruel hoax that dismantles Medicare and does not provide seniors an affordable, defined, guaranteed Medicare prescription drug benefit.”

Daschle bitterly warned that AARP’s move will come back to haunt the high-profile organization.

“Like the AARP’s previous decision to support the 1988 catastrophic health bill, this is a mistake that does not serve the interests of its members,” said Daschle, who told reporters the group “caved in” to Republican pressure. “Public opinion polls have long showed that seniors strongly oppose the kinds of radical changes to Medicare proposed in this legislation, and when seniors see the details of the Republican plan, the AARP leadership will undoubtedly regret this ill-advised decision.”

Daschle has not made a call on whether he will lead a Democratic filibuster of the Medicare bill, which could be risky politically given AARP’s decision to back the legislation — as well as the Senator’s own re-election bid back home.

AARP released its own statement announcing its “strong endorsement” of the GOP-drafted bill, which is also being supported by Democratic Sens. Max Baucus (Mont.) and John Breaux (La.), both of whom were included in high-level talks that yielded the final agreement. The new benefit is estimated to cost $400 billion over 10 years.

“AARP believes that millions of older Americans and their families will be helped by this legislation,” the group declared in its statement. “Though far from perfect, the bill represents an historic breakthrough and important milestone in the nation’s commitment to strengthen and expand health security for its citizens at a time when it is sorely needed.”

William Novelli, executive director and CEO of AARP since January 2000 following a stint running the Campaign for Tobacco Free Kids, told The Associated Press that his organization “will pull out all the stops,” including the ad campaign. Novelli is a former public relations industry executive.

Novelli and AARP officials, who have been courted heavily by Bush and other top Republicans over the past several months, made the judgment that the federal government’s weak fiscal outlook over the next few years made getting a deal now imperative — before the situation worsens.

“There’s $400 billion that has been set aside right now” for a Medicare prescription drug benefit, said Steve Hahn, an AARP spokesman. “It’s hard to say if it would ever come back again.”

But it looks like the White House isn’t stopping at AARP alone. On Sunday afternoon, Bush began placing calls to moderate Democrats to lobby them to back the bill, and GOP insiders expect to work a one-two punch with AARP to convince rank-and-file Democrats to support the legislation even if their party leaders oppose it.

If Democrats do not come aboard, these Republicans warn, they can expect to see campaign ads next fall telling their constituents that they voted against a prescription drug bill backed by AARP.

“AARP gives you the Good Housekeeping Seal of Approval when it comes to seniors’ issues,” said Hastert. “They care deeply about the future of Medicare and they wouldn’t endorse something that would lead to the end of that program as some critics contend.”

The political bind that Democrats now find themselves in demonstrates how important AARP’s endorsement was for Bush, Hastert and Senate Majority Leader Bill Frist (R-Tenn.), who will have to overcome significant opposition from within their own ranks to pass a Medicare bill.

While other organizations like the American Medical Association and the American Hospital Association have backed the Medicare deal, none has the cache of AARP.

After word of AARP’s decision broke, Democratic leaders began working to keep their Members unified in opposition to the measure. Several well-placed Democratic sources said their leaders are likely to make the vote a “party call,” or one on which all Members are expected to side with the leadership or else.

“Again, this is a classic example of how Democrats get screwed in the minority,” added a senior House Democratic staffer. “The Republicans come out with a bill and put us between a rock and hard place.”

Nine Democrats defected to side with the GOP when the prescription drug bill hit the floor in June. Several Democratic leadership sources said they are hoping to hold that number at nine or less on the conference report, which they acknowledge will be difficult.

House Democrats, in anticipation of a controversial Medicare vote, have been holding top-level whip meetings on the topic for months, and began formally whipping the vote over the past two weeks.

There were no good estimates of how many conservative House Republicans will have to be turned to support the bill, although a number of right-wing GOP lawmakers have objected to the newest government intrusion in the marketplace, and influential conservative groups such as the Heritage Foundation will oppose it. Now that a bill is in place, Republican leaders plan to start meetings with their rank-and-file Members to sell them the package.

“It’s gonna take some work, but I think it’s doable especially now that AARP is out there,” said a top GOP staffer.