Forget about winning over their political opponents. As they float plans to solve the debt ceiling impasse, President Barack Obama and Senate Minority Leader Mitch McConnell (R-Ky.) are having a difficult enough time with their own parties’ activists.

Obama’s talk of cuts to major entitlement programs has triggered a massive advertising and grass-roots lobbying campaign from groups that usually have the president’s back. On the other side, McConnell’s proposed fallback option to free Obama to raise the debt limit, possibly without spending cuts, has roiled fiscal and tea party conservatives.

“Our members … worked incredibly hard to elect this president and were shocked that he would endorse cuts to Social Security and Medicare benefits,” said Justin Ruben, executive director of MoveOn.org.

His group released a poll of its members that showed 76 percent of respondents would be less likely to donate to or volunteer for Obama’s campaign if he cut Social Security. And the Progressive Change Campaign Committee on Friday will deliver a petition with more than 180,000 signatures to the Obama campaign headquarters in Chicago warning the president that if he cuts entitlements, “don’t ask for a penny of my money or an hour of my time in 2012.”

A grand bargain that couples cuts to Medicare, Medicaid and Social Security with tax increases might now be off the table, and McConnell’s plan faces stiff resistance. But that hasn’t stopped the barrage of ultimatums. Some organizers are seizing on the debt limit debate to send a political message, running ads in Iowa, New Hampshire and targeted Congressional districts.

The strongest outcry has come from groups such as MoveOn.org that are traditionally allied with Democrats, whose leaders acknowledge they’re playing catch-up with anti-tax activists who weighed in early. Labor, women’s and liberal activists have organized rallies, conference calls, Web videos, pledges and calls to Congress, all aimed at blocking entitlement changes.

Even a group of 4,000 pastors of various denominations signed an open letter to Congress that opposed budget cuts.

Activists from the left have generated thousands of calls to House Democrats, urging them to sign on to a letter authored by the Congressional Progressive Caucus. The letter, organized by the caucus’s co-chairmen, Reps. Keith Ellison (D-Minn.) and Raúl Grijalva (D-Ariz.), calls for entitlement cuts to be “taken off the table.”

MoveOn.org also released a series of Web videos Wednesday targeting 10 Republican House Members with the message that GOP threats to block a debt limit increase could “crash the economy.”

On both sides of the ideological divide, organizers said the fluid and unpredictable nature of budget negotiations has proved to be a challenge.

“This debate has changed constantly,” said Pamela Causey, communications director for the National Committee to Preserve Social Security and Medicare. “One day, Social Security is off the table, and the next day, it is on the table. It’s hard to plan very far down the pike because you don’t know what [will be] the next time bomb waiting for you that you need to address.”

Causey’s group will unveil a six-figure TV ad campaign this weekend.

Other groups representing senior citizens also jumped into the fray in a major way this week. AARP on Tuesday announced a multimillion-dollar TV ad buy spotlighting the tagline: “Tell the politicians: Cut waste and loopholes. Not our benefits.”

Organizations representing the disabled brought families that would be affected by Medicaid cuts to the White House and to Capitol Hill this week.

“Medicaid has not until very, very recently had a voice at the table,” said Michael Hill, senior vice president for communications for United Cerebral Palsy. The group is working with the American Association of People with Disabilities on a campaign to bring “that human face to the discussion of the debt ceiling, particularly around Medicaid,” AAPD President and CEO Mark Periello said.

Anti-tax and tea party organizers are delivering the opposite message to Capitol Hill: Don’t raise the debt ceiling without sweeping concessions. Many have rallied behind a Cut, Cap and Balance plan that would combine spending cuts and caps with a constitutional amendment to balance the budget.

The Club for Growth went on the air this week with ads targeting Republican Sens. Orrin Hatch (Utah) and Dick Lugar (Ind.), warning them not to raise the debt ceiling without demanding cuts. GOP Sens. Mike Lee (Utah), Rand Paul (Ky.) and Pat Toomey (Pa.) have introduced a Cut, Cap and Balance Act in the Senate.

The pro-GOP Crossroads GPS has launched a $7 million ad campaign also tied to the debt limit debate. Some ads target Obama, exhorting viewers to take away his “blank check.” Others cast Democratic Sens. Sherrod Brown (Ohio), Claire McCaskill (Mo.), Bill Nelson (Fla.), Ben Nelson (Neb.) and Jon Tester (Mont.) as backers of higher taxes and new debt.

A new conservative advocacy group called Public Notice Research & Educational Fund has released an online ad with the message: “Washington could learn a lot from a drug addict.” It compares politicians hooked on raising the debt limit to junkies.

And tea party organizers and conservative groups such as Let Freedom Ring — which is leading the Cut, Cup and Balance campaign — have focused their fight on McConnell.

“Mitch McConnell’s plan shows plainly he wants to abdicate any responsibility for fiscal matters to the President,” Mark Meckler, a national coordinator of the Tea Party Patriots, said in a statement.