NEW YORK (CNN/Money) - My husband and I have visited two financial advisers, but can't get a straight answer to a straight question. We want to know if our retirement portfolios that are worth about $535,000 can provide us with an income of at least $25,000 for the rest of our lives. The advisors want us to sign up before they'll tell us. Do you think we can pull this off?

-- Susan Mattingly, Crestwood, Kentucky

First, in fairness to the financial advisers you contacted, let me say that they may have been reluctant to give a quick yes or no to what is actually a fairly complicated question.

Before a financial planner or other adviser can say for sure whether you can get the income you want from your portfolio, he or she would probably want to get a lot more information about your finances, talk to you about how much investment risk you feel comfortable taking, what other sources of income, if any, you have access to, whether you plan to leave a legacy to heirs and, if so, how big a legacy, etc.

So it's entirely possible that the advisers felt you were trying to milk an answer out of them they didn't feel they could give, or didn't want to give until they had more information to work with, which would involve time and effort on their part.

All that said, however, it seems to me you've got a decent shot at getting the income you need for a very long period -- you didn't give your age, but I'm thinking a retirement lasting 30 years or more -- although it is by no means a certainty. So you see, I too, am waffling a bit on your "straight question."

One reason I'm hedging my answer is that I'm not sure exactly what you want -- or that you do either. You say you need $25,000 a year. But I suspect you really want $25,000 adjusted for inflation.

I mean, the $25,000 you use to buy groceries, pay utilities, travel, etc. this year isn't going to get you the same amount of food, utilities and travel 10 years from now. Assuming inflation of, say, 2 percent per year, you're going to need about $30,500. So to prevent your standard of living from declining as you age, you're going to have to increase your annual $25,000 draw, which will put more of a strain on your portfolio than merely pulling out the same 25 grand every year.

RELATED ARTICLES • What's a fair fee? • Finding a helpful financial adviser • Looking for a good adviser

Basically, you're talking about an initial withdrawal equal to just less than 5 percent of your portfolio's value. It may seem as if you should have no trouble pulling out that amount even adjusting for inflation. But if you run into a big market downturn -- especially in the early years of retirement -- even withdrawals of that size could be difficult to sustain without draining your assets.

You'll improve your odds significantly if you lower your initial withdrawal to, say, 4 percent of your portfolio. But even then you don't have a 100 percent guarantee your portfolio will last as long as you live.

The other big driver of how much you'll be able to draw from your portfolio is how you allocate your money between stocks and bonds.

A mix tilted more toward bonds will probably produce a lower return over the long term, which would generally make it harder to achieve your goal than a mix tilted toward stocks. Then again, the more stocks you have, the more your portfolio's value will jump up and down.

Big variations can scare many investors, especially people relying on their portfolios for retirement income. So you'll want to arrive at a portfolio mix that gives you a reasonable degree of certainty that you can get the income you want, but doesn't leave you constantly worrying whether your portfolio might tank during a market setback.

Arriving at that kind of mix means spending some time with an adviser who can explain the implications of various mixes of stocks and bonds -- and who's willing to factor your comfort level into the decision.

My advice is that you try a few more advisers. (If you'd like some referrals, you can try organizations such as the National Association of Personal Financial Advisors, the Financial Planning Association and the Garrett Planning Network.)

But rather than presenting this as a question that requires an immediate response, explain to them what your goals is and say you'd like to hear what process they would go through to assess whether that goal is realistic and, if so, how to achieve it. Most advisers will offer potential clients a short initial consultation at no charge or for a small fee.

During such a consultation, you should be most interested in what type of analysis the adviser will go through to create a retirement income and investing strategy for you. Ideally, the adviser should have access to "Monte Carlo"-type software that generates thousands of simulations of a variety of different scenarios into the analysis to incorporate the uncertainties of the financial markets into the portfolio-building process.

The adviser may also want to suggest adding one or more income annuities to your holdings in order to generate some income that's guaranteed to last the rest of your life. The important thing, though, is that the adviser should be able to show you that he or she is familiar with the issues involved in creating a retirement income -- and convince you that your interests come before considerations like earning a big sales commission or selling a particular product. (Caveat: if an adviser's solution is as simple as putting all or nearly all of your money in an annuity, move on!)

Over the course of such an initial consultation and by contacting some references of people for whom the adviser has already helped create such an income plan, I think you should be able to get not only a straight answer to your question, but come away with a better appreciation of the various choices and tradeoffs involved.

Walter Updegrave is a senior editor at MONEY Magazine and is the author of "Investing for the Financially Challenged." He also answers viewers' questions on CNNfn's Money & Markets at 4:40 PM on Monday afternoons.