“Tonight, I propose a new tax cut for homeownership that says to every middle-income working family in this country, if you sell your home, you will not have to pay a capital gains tax on it ever — not ever.”--— President Bill Clinton, at the 1996 Democratic National Convention

Ryan J. Wampler had never made much money selling his own homes.

Starting in 1999, however, he began to do very well. Three times in eight years, Mr. Wampler — himself a home builder and developer — sold his home in the Phoenix area, always for a nice profit. With prices in Phoenix soaring, he made almost $700,000 on the three sales.

And thanks to a tax break proposed by President Bill Clinton and approved by Congress in 1997, he did not have to pay tax on most of that profit. It was a break that had not been available to generations of Americans before him. The benefits also did not apply to other investments, be they stocks, bonds or stakes in a small business. Those gains were all taxed at rates of up to 20 percent.

The different tax treatments gave people a new incentive to plow ever more money into real estate, and they did so. “When you give that big an incentive for people to buy and sell homes,” said Mr. Wampler, 44, a mild-mannered native of Phoenix who has two children, “they are going to buy and sell homes.”...

The change in the tax law had its roots in a Chicago speech that Senator Bob Dole, Mr. Clinton’s Republican opponent in the 1996 presidential election, gave on Aug. 5 of that year. Trailing Mr. Clinton in the polls, Mr. Dole came out for an enormous tax cut, including an across-the-board reduction in the capital-gains tax.

The proposal made Mr. Clinton’s political advisers more nervous than almost anything else during the campaign. The campaign’s chief spokesman, Joe Lockhart, traveled to Chicago to stand outside the ballroom where Mr. Dole was speaking and make the case that the Dole tax cut would cause the deficit to soar.

At the same time, Mr. Clinton’s aides began scrambling to come up with their own tax proposal. Dick Morris, the president’s chief outside political adviser, argued that Mr. Clinton could assure his re-election by matching Mr. Dole’s call for a big cut in the capital-gains tax.