While saving Social Security (search) became a familiar mantra on the campaign trail, President Bush and members of Congress now actually face the prospect of handling real legislation for reform, and politicians are already lining up along party lines for a fight.

"This is going to be one of the hottest issues of the year," said Peter Ferrara, director of the Club for Growth’s (search) Project on Social Security. "We have to do something before the [midterm] election."

Getting started on the topic, 16 congressional leaders met Monday with Bush to discuss the alternatives being offered by lawmakers and to consider what kind of proposal the White House will make regarding the big Social Security fix.

Bush campaigned for re-election on private investment accounts for workers, who would be able to set aside a portion of the taxes they pay into the system for a separate, wholly owned retirement fund, as recommended by the commission he appointed to study various Social Security reforms in 2001. The commission suggested allowing diversion of 2 percent of contributions from employees into private accounts. The remaining 4.2 percent, and the taxes employers pay, would go into the system to help pay for benefits for current retirees.

White House spokesman Scott McClellan said Monday that the president has not endorsed any specific plan yet, but he expects that the "upfront transition financing" — now estimated at $2 trillion — will be paid for with government borrowing.

"Under the current system, the cost of doing nothing is $10 trillion over the long haul," McClellan said.

The president is expected to make a major announcement during his economic conference at the White House later this month, but until he does, speculation is running high regarding what members of Congress will have to fight for — and against — in the upcoming debate over Social Security.

"In order to debate it properly, we need to know what will be in it," said Dan Maffei, spokesman for Rep. Charlie Rangel, D-N.Y., the ranking Democrat on the House Ways and Means Committee, which gets first crack at proposals introduced in the House.

Sen. John Kerry is in line to be the ranking member of the Senate Finance Committee, which will be the first to handle proposals in that chamber. He has said he opposes what he calls Social Security "privatization schemes," and has vowed to fight them off in the upcoming session.

Maffei said the majority of Democrats in the House caucus agree that Social Security should undergo modest changes in payroll taxes, benefits and the retirement age, but a major overhaul would add to massive deficits and increase the vulnerability of future retirees to fluctuations in the stock market. Though they are in the minority in both chambers, Democrats are vowing to stir up a hornets’ nest of protest against private accounts once a plan is on the table.

"I do believe Democrats are going into this debate as united as they have ever been," said Maffei.

Meanwhile, Republicans say they have a mandate from voters who elected pro-reform candidates throughout the country this year, including the president. Unlike years past, when the issue had been stalled because of a lukewarm response from voters, the time is ripe for action, they say.

"I have put six years of my life into this thing, I want to see it get done," Rep. Clay Shaw, chairman of the House Ways and Means Social Security subcommittee, told FOXNews.com.

Shaw has introduced a bill that would allow workers to invest up to 3 percent of their payroll taxes into federally approved portfolios. The new system would not take money out of the current system to pay for this, rather it would borrow against the federal government before becoming self-sustaining in another generation.

Other Republicans also have introduced legislation to privatize the system. Sens. John Sununu, R-N.H., and Lindsey Graham, R-S.C., and Rep. Paul Ryan, R-Wis., say not only will the old system stop paying for itself in 2018, but anyone who retires in another 50 years will get only 75 percent of the benefits promised to them. In short, something needs to be done.

Ryan’s plan would allow an average of 6 percent of payroll taxes for personal accounts and would require, in part, borrowing the money and cutting the growth of federal spending, to finance it.

"It democratizes capitalism, it brings every single worker in America into the ownership society," Ryan told FOXNews.com.

"Workers will get more money they would otherwise not get and it’s all theirs," he said, asserting that existing benefits will not be cut nor taxes raised.

Lower-income workers are allowed to invest more of the taxes than higher-income workers and everyone who volunteers for the accounts will be guaranteed to walk away with at least what they put into the current system, under his plan, Ryan said.

"I think we will find out this is a proposal that has the power to give lower- and middle-income workers access to retirement accounts that create real opportunities for much greater financial security," said Sununu, whose companion bill to Ryan’s legislation was introduced in September.

Sununu's plan does have some competition from Graham, whose bill allows for workers 54 years old and younger to put 4 percent of their payroll taxes into investment accounts, but uses price indexing and raises payroll taxes to pay for it.

McClellan said the president is committed to not raising taxes, a principle consistent with his first term, but that he wants to work closely with Graham and other lawmakers to get the reforms done.

Graham told FOXNews.com that he is "very open-minded about ideas" on how to achieve sustained solvency.

Under Graham's legislation, benefits and payments for those over 55 are left untouched, and McClellan said Bush wants to make sure that people "at or near retirement age" are not affected by the legislation.

But Democrats, backed by the AARP, the nation’s largest senior citizens’ advocacy group, don’t buy assurances that current or future benefits won’t be cut, and complain that enticing people out of the program will only destroy the bedrock institution.

"[Personal accounts] do not improve solvency, no matter how you are looking at it," said Evelyn Morton, AARP’s national coordinator for economic issues.

"If you tell people they will have to sustain cuts in their benefits in order to finance these accounts they become less attractive," she said, adding that the AARP will work with other groups to get that message out.

The AARP believes that incremental changes, like raising the cap on taxable wages, might work to resolve the solvency problem, which many Democrats don’t believe is as dire as Republicans make it out to be.

Meanwhile, some conservative Blue Dog Democrats have supported personal retirement accounts for years while some Republicans say they oppose any efforts to "privatize" the system because their own constituents are fickle and not sold on the idea. Debate continues among other Republicans over how personal accounts should be financed.

Graham said no matter whose plan emerges as the front-runner, some Democrats will have to get on board if any reforms are to occur.

"Democrats are going to have to swim upstream to embrace the personal-account solution. Republicans are going to have to come up with a financing plan that's realistic," Graham said.

The president’s coming announcement is likely to spur the political drama that lies ahead. For those who have waited patiently for years to get a real debate over this politically sensitive issue started, they can't wait for it to begin.

"The problem is if the far left in the Democratic Party and the far right in the Republican Party get together to kill this thing," Shaw said. "I hope to God that doesn’t happen, but it’s something we need to be conscious about."