The Obama campaign's descending eligibility thresholds went like this:

-- In July: "If you make $250,000 a year or less, we will not raise your taxes. We will cut your taxes," Obama said in remarks at Powder Springs, Ga., on July 8.

-- In October: "If you have a job, pay taxes and make less than $200,000 a year, you'll get a tax cut," Obama said in a widely shown TV ad titled "Defining Moment."

-- Last week: "What we're saying is that (Bush's tax cuts to the wealthy) ... should go to middle-class people -- people making under $150,000 a year," Biden said in an interview with WNEP in Scranton, Pa., on Oct. 27.

-- Last Friday: "What Obama wants to do is he is basically looking at $120,000 and under among those that are in the middle class, and there is a tax cut for those (people)," Richardson said in an interview Friday on KOA-AM in Denver.

The dissolving tax-cut numbers left economists on both sides of the aisle scratching their heads and wondering just who would really benefit from Obama's tax plan and who would not.

"Every time we look, his plan changes. Anything is possible," said Kevin Hassett, an economist at the American Enterprise Institute and a McCain adviser. The Obama campaign's high command denied that Obama had moved away from his original tax-cut plan. Chief spokesman Bill Burton said that Richardson "simply misspoke."

But the governor, who has cut income taxes across the board in New Mexico, is fluent with tax numbers and many analysts say the senator's numbers "don't add up" and wouldn't yield the revenue he said it would to deliver his promised tax cuts.

The Democrats do not have a good track record on delivering middle-class tax cuts. Bill Clinton promised them in 1992, only to abandon the idea in the face of a mounting budget deficit.

The federal government will be looking at a $1 trillion budget deficit in 2009 in the midst of a possibly long recession, making Obama's tax cuts less likely, even in next year's much more liberal Democratic Congress.