There are several ways to measure the "size" of the president's tax cut plan. Officially, when all its provisions have been fully phased in, the plan will drain about $350 billion from the treasury between now and 2013 -- which is itself not a small amount, considering what else that money might have purchased. The $350 billion price tag, though, is smaller than the president's initial $726 billion proposal and the House's $550 billion plan.

The relatively smaller size of the tax cuts enacted into law is something of an optical illusion, however. Thanks to some skillful budget trickery, Bush's tax cut is still a massive cut, albeit squeezed into a (relatively) small package. In order to keep the advertised 10-year price under the $350 billion limit, Republicans allowed many of its provisions to "sunset," or expire, before 2008.

But if the Republicans continue to control Congress and the presidency, it is likely that many -- or all -- of these provisions will be extended. In that case, the bill's 10-year price would be between $807 billion and $1.06 trillion, according to the Center on Budget and Policy Priorities.

Conservatives make no apologies for the sunset gimmick. Grover Norquist, the head of Americans for Tax Reform and a close friend of the Bush White House, calls the tax cut "a thing of beauty" and says that the moderates and Democrats got what they deserved for putting an arbitrary cap on tax cutting.

Besides, according to Bush, the tax cut is the key to sparking new growth and creating millions of new jobs. During his speech at the bill-signing ceremony Bush said the word "jobs" about a dozen times. It's obvious why. During his time in office, about 2.7 million people have lost their jobs. The White House projects that the new tax cut will create 1.4 million new jobs, but, as many Democratic lawmakers note, that would still leave Bush the only president since Herbert Hoover to have presided over a job-losing economy. (Interestingly, Hoover, too, was aided by a Republican-controlled Congress.)

The idea of giving Americans spending money to help the economy "get a good wind behind it" does not, strictly speaking, conform to bedrock Republican theories of how economies ought to function. Conservative economists ("supply-siders") do not generally believe that output grows simply because people have more money to buy things -- if they thought so, they'd support government welfare.

Instead, many conservatives -- including the president's advisors -- think that real growth occurs only when people react to lower tax rates by working harder or by investing more. What's striking about George W. Bush is that in two years of selling some of the largest supply-side tax cuts in history, he's hardly ever made that case. Indeed, he's never made any single coherent argument for "tax relief." Instead, since his campaign, he's constantly tailored his pitch to fit the prevailing political mood. As the New York Times reported on Feb. 5, 2002, "He has argued that tax cuts are necessary when the nation is flush with prosperity and when it is in the economic dumps, in peacetime and in wartime, to get rid of the budget surplus and to restore it."

For jobs to be created, the economy would have to grow, and there is plenty of dispute about whether this tax cut will make that happen. In a paper he wrote in March, Richard Kogan, an economist at the Center on Budget and Policy Priorities, noted that Macroeconomic Advisers, an economic consulting firm, determined that in the long run, the president's package as it was initially proposed would reduce economic growth.

The assessment by Macroeconomic Advisers, Kogan wrote, "is especially significant because the President's Council of Economic Advisers uses the economic model that Macroeconomic Advisers developed." The firm said that at first, "the plan would stimulate aggregate demand significantly by raising disposable income, boosting equity values, and reducing the cost of capital." But because of its huge cost, the plan also reduces national savings, which will lead to increasing interest rates. "By 2017 the effect would be to reduce the level of potential GDP by about 0.3 percent and raise long-term interest rates by about 0.75 percentage points."

When asked about such models, conservatives often dismiss them and point to the Reagan years, when, they say, tax cuts led to strong economic growth. But a close look at the Reagan years doesn't support their claims. In the '80s, the postwar decade in which the United States enjoyed the lowest marginal tax rates, economic growth averaged about 3.2 percent per year. The trouble is, as Kogan points out, that such growth was not all that much better than growth in other decades. In the '90s, for example, a decade in which marginal taxes were raised and the United States experienced record surpluses, economic expansion averaged 3.1 percent a year. When you adjust for the population differences between the two decades, the growth per person in the 1980s is identical to that of the 1990s. The '70s, too, had similar growth -- about 3 percent. In other words, for all the conservative reverence for Reaganomics, the strategy two decades ago does not appear to have added any significant boost to the economy -- which makes it curious that the Bush administration is still pushing the same plan, especially when you think about the endless deficits it will entail.

Unless endless deficits are the goal.

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