SAN FRANCISCO (MarketWatch) -- If you haven't yet had your credit limit slashed on one of your credit cards, it's highly likely you will -- if Meredith Whitney is right, that is.

Whitney, an analyst and managing director at Oppenheimer & Co. who predicted the current financial-services industry meltdown, now says credit-card issuers will eliminate more than $2 trillion in available credit over the next 18 months.

Already, lenders have cut back on available credit due to their heightened aversion to risk and difficulty in funding loans. Before the financial crisis, consumer loans could be sold on a secondary market and the proceeds could help to spur more lending, but that market has largely dried up. See Consumer Watch on card issuers raising interest rates, fees.

Whitney warns that new accounting rules that will force lenders to record outstanding credit-card loans on their balance sheets, combined with the Federal Reserve's expected changes in credit card regulations -- including limiting lenders' ability to raise rates on consumers' existing debt -- will prompt them to cut access to credit lines even more.

"Restricting lenders' ability to reprice an unsecured loan will cause them to stop lending or to lend less," Whitney said in a recent opinion piece in the Financial Times. Whitney was unavailable to comment for this article. See story on Federal Reserve's upcoming changes to credit-card rules.

To the degree that limited access to credit dampens consumer spending further, that could severely hinder an economic recovery. See story on biggest drop in consumer spending in seven years.

"Specific to the credit-card industry, we believe that well over $2 trillion of lines will be pulled over the next 18 months, the result of risk aversion and funding challenges, but also regulatory and accounting changes," Whitney and her colleagues wrote in a Nov. 30 research report.

"The severe consequence of this cannot be overstated," the report said. "While just over 70% of U.S. households have credit cards, over 90% of those households revolve credit at some point during the year, or in other words use credit card lines as a cash management vehicle.

"Pulling credit at a time when job losses are increasing by over 50% year on year in most key states is a dangerous and unprecedented combination, in our view," the report said.

Still, some economists note that many consumers have access to credit lines -- often tens of thousands of dollars' worth -- that they don't use.

"There are plenty of middle- to higher-income folks out there who may have a $20,000 line on their credit card but they rarely use more than $2,000 of it. If you knock that line down to $4,000 or $5,000, so what?" said Scott Hoyt, senior director of consumer economics at Moody's Economy.com. "There is another set of consumers who may have a $2,000 credit line and are borrowing $1,500, $1,800 on an ongoing basis. If you whack their credit line, that's going to impact them pretty severely," he said.

"Without knowing how the distribution [of the pull-back in credit] is going to fall among consumers and how much of a utilized line is going to be cut, it's really hard to say what the overall impact is going to be," Hoyt said.

Cutting $2 trillion still leaves $2 trillion

Bill Hampel, chief economist with the Credit Union National Association, noted that there's almost $1 trillion in outstanding credit-card debt currently -- it's about $976 billion according to the latest Federal Reserve figures -- and the current ratio of borrowing against available credit is about 20%, according to FDIC figures.

"That means there is about $5 trillion outstanding now of available lines of credit," he said, with about $1 trillion of it borrowed. If Whitney is right and about $2 trillion of available credit is eliminated, that still leaves about $2 trillion available -- twice as much as is currently tapped by consumers, Hampel said.

Still, he's quick to add that "doesn't mean [further credit cuts] would have no effect."

For instance, consider consumers who are carrying a balance and for whom a decrease in credit limit would put them much closer to their limit. "Bingo. They'd stop spending on that card," Hampel said.

Plus, there's a psychological effect on consumers. "If households thought they had less of a liquidity back-up available on their credit cards than they did before, that would reduce spending."

Others agreed the overall effect is hard to judge, as it depends heavily on which consumers are affected. Thus far, credit-card issuers appear to be both focusing their efforts on the least creditworthy borrowers as well as making across-the-board changes regardless of borrowers' credit standing.

Some lenders have pulled lines "from certain perceived high-risk ZIP codes or areas of weakened home values; others have pulled more uniformly," according to the Oppenheimer report, which focused on the five biggest credit-card issuers.

Peter Morici, an economist and business professor at the University of Maryland, said that his own credit-card interest rate has been raised. "Everybody is getting their rates raised, no matter what their status is. I have sparkling credit, I haven't borrowed in years, and [I have] a large income ... they raised my rate," he said.

"It doesn't affect us ... but it does affect those people who do carry balances and there are a lot of them out there," he said. "It's people often with small incomes who get in a jam -- they need to fix their car. This is going to come down really hard on the working poor or the lower middle class. The banks are trying to balance their books on the backs of the poor," he said.

Plus, the current state of the job market poses a major risk. "A lot of people haven't been using credit. If they lose their jobs, they're going to start to," Morici said.

What you can do

For consumers who find their credit limit cut or interest rate raised, there are not a lot of options:

Depending on the terms of your credit-card agreement and the laws governing the credit-card issuer, which vary depending on the state in which the company is chartered, the credit-card issuer may offer an opt-out provision when raising interest rates. That means you can contact your lender to tell them you will pay off your balance at the current rate but will close your account (that may happen immediately or after the balance is paid off, depending on the lender's terms).

A lower credit limit will often ding your credit score. One way to bring your score up is to pay down your debt. If you can't do that immediately, another solution is to call your lender and seek a higher limit. They may listen to a borrower with top-tier credit.

Another option is to seek credit elsewhere. Try a small regional bank or a credit union. If you have good credit, "credit unions, and I suspect small banks, too, still have room on their balance sheets to take on additional loans," Hampel said.

If you find yourself falling into a financial vortex due to rising credit-card bills, consider contacting a consumer credit counseling agency. Try the National Foundation for Credit Counseling at NFCC.org or the Consumer Credit Counseling Service of San Francisco, which works with consumers nationwide, at CCCSSF.org. You won't be alone. Calls to NFCC increased 87% in the second week of November and 170% in the third week of November, compared with the same time periods a year ago.

Also, the traditional personal-finance advice exhorting consumers to pay off credit cards before doing anything else may be turned on its head these days.

"The old advice was that you would pay off your credit cards and the credit cards would be there as emergency backup," said Gerri Detweiler, a credit adviser with Credit.com. "You might want to start stockpiling some savings before you aggressively pay down cards, so you have liquid savings as a back-up in case your issuer does close the credit line. Once you have at least somewhat of a cushion, then you can go ahead aggressively try to pay down your credit card," she said.

"Financially it's not going to save you the most money, but it's the new reality for a lot of consumers who have assumed that credit would always be there for them."