Lots of Democrats have problems with the big tax deal President Obama made with Republicans. They don't like the extension of the Bush tax cuts for the wealthy. They don't like the provision on the estate tax. And some are getting heartburn over the proposed reduction in Social Security taxes because they worry it could seriously weaken the program.

The Social Security piece of the controversial tax package seems like something most taxpayers would welcome. Every worker who pays Social Security payroll taxes would see them cut to 4.2 percent from the current 6.2 percent. The maximum tax break would be a little over $2,000, and the cut would expire after one year.

Obama certainly seemed pretty pleased with the provision when he described the deal in a news conference on Tuesday.

"As a result of this agreement we will cut payroll taxes in 2011, which will add about a thousand dollars to the take-home pay of a typical family," he said. "So this isn't an abstract debate. This is real money for real people."

It's a good deal for the American people, Obama said. But the payroll tax cut makes Nancy Altman very nervous.

"This could eventually lead to the unraveling of Social Security," says Altman, a co-chair of the advocacy group Social Security Works.

She says it might look like a harmless one-year boost for struggling Americans. But Altman is certain Republicans will try to make the payroll tax cut permanent, which, she says, could lead to trouble for Social Security.

"The Bush tax cuts were supposed to be 10 years," she says. "And we see now that it's very hard once a tax cut is in place to repeal it. The fear is that once this cut is made it becomes permanent and all of a sudden Social Security's shortfall, which is very manageable at this point, would actually double."

Under the one-year deal hatched by Obama and Republican lawmakers, Social Security's long-term financial problems would not worsen. That's because the retirement program's trust fund would be reimbursed for its lost tax receipts. The money would come out of general revenues, the same pot that pays for food stamps and defense. But Altman, and some Democratic lawmakers, worry that if the payroll tax cut becomes permanent, Congress will balk at making up the shortfall year after year with general revenues.

"If we start to fund Social Security through general revenue," says Rep. Ted Deutch, a Florida Democrat, "given where we are today, through deficit spending, it will permit those who would like to, [to] move away from our long-standing, successful Social Security program to privatization and to benefit cuts. It will enable them to make those arguments in a way that they've never been able to make them before."

Deutch says he has no doubt that a year from now some Republicans will try to make the payroll tax cut permanent.

Republican Sen. Bob Corker of Tennessee is predicting the same thing. He says that a year from now when the tax break expires it will be portrayed as a tax increase.

And Republican Sen. Mike Johanns of Nebraska agrees.

"I anticipate that somewhere along the line somebody's going to make that argument, whether I agree with it or not," he says.

In any case, Johanns warns against "messing with Social Security."

"We've got to get back to the reality that this is a system that needs our thoughtful consideration on how best to improve it," he says.

There's no question that the White House understood it was taking a risk. But the administration couldn't persuade Republicans to renew a stimulus program targeted at lower-income workers. So, with the economy continuing to struggle, the White House opted to embrace the stimulus provided by the Social Security tax cut, and worry about the repercussions a year from now.

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