WASHINGTON — Senator Obama will likely have another talking point at the Democratic National Convention tomorrow when the Census Bureau releases data on poverty, income, and the number of uninsured.

The annual report provides grist for both parties in the high-pitched debate over the economy, and both liberal and conservative analysts predict the new data will yield little good news.

The number of Americans without health insurance is expected to rise, analysts from the left-leaning Economic Policy Institute and the right-leaning American Enterprise Institute said. The predictions diverge on the poverty rate, with AEI expecting a slight increase and a senior economist at EPI, Jared Bernstein, forecasting a small drop.

The Bush administration may take more comfort in the median household income, which economists predict could show a modest increase for the second consecutive year. But the figure is not likely to jump high enough to equal the median income level when President Bush took office, giving Democrats more fodder for their argument that the administration’s economic policies have failed to improve the standard of living for most Americans.

The number of Americans without health insurance reached a high of 47 million in 2006. The rise in the uninsured, combined with skyrocketing overall costs for health care, put the issue at the center of the presidential election throughout 2007 and earlier this year, although it has since been eclipsed by concerns over gas prices.

The new numbers should force the issue to the fore once again. “It’s almost for certain that there will be an increase in the number of uninsured. That will lead to even more calls for coverage of the uninsured by the government and paid for by the taxpayers,” a resident scholar at AEI, Douglas Besharov, said.

The presidential candidates each have ambitious health care plans and have fought for months over which proposal will cover more people. Mr. Obama’s proposal expands government options for insurance while Senator McCain relies on large tax credits to encourage people to buy their own insurance instead of relying on employer-provided coverage.

Critics of the Census measure of the uninsured say it dramatically overstates the number of Americans without access to health care, leading to a political outcry that the system is in crisis. The figures are “inaccurate and hugely exaggerated,” the president of the National Center for Policy Analysis, John Goodman, said. The statistics given by the Census Bureau, he said, obscure the number of people who are eligible for government health care programs but are not enrolled. And, he said, data show that more than one-third of the uninsured live in households earning more than $50,000 a year, meaning they could likely afford some health insurance.

Tomorrow’s report will cover data from 2007, which many analysts view as the final year of the economic recovery from the recession at the beginning of the decade. Economic growth has slowed further in 2008, and some economists believe a recession has begun, so the news next year is likely to be even more sobering.

“2007 is as good as it gets, and it’s not that good,” Mr. Bernstein of EPI, an informal adviser to the Obama campaign, said.

While the economy has expanded and unemployment has remained low for much of Mr. Bush’s two terms, Mr. Bernstein said the numbers will likely demonstrate that this decade’s economic recovery will be the first in which median household incomes have not returned to their pre-recession peak.

“What you have here is evidence that there is no trickle down,” he said.

Mr. Besharov of AEI said conservatives should not try to sugarcoat the data, acknowledging that the recovery has been relatively “anemic” and that the last year has been particularly rough for low-income Americans. “It’s really important to recognize that it was not a great 12 months,” he said.

At the same time, he criticized the tendency to place the blame squarely on the Bush administration. “You have a lot of forces at work,” he said, citing in particular the effects of globalization and the rise of China and India as economic competitors. “There were long-term macro-trends, and some can be dealt with through policy, and some will just require adjustments.”

The Census Bureau reported a poverty rate of 12.3% for 2006, which represented a small drop from the previous year. The median household income grew to $48,201 for the second consecutive year after a period of decline.

Messrs. Obama and McCain are certain to issue statements responding to the data, but one prominent Democrat who is unlikely to be heard from tomorrow is John Edwards. The former North Carolina senator and 2004 vice presidential nominee emerged as the party’s most vocal champion of the poor during his failed White House bid earlier this year, and he secured commitments from both Mr. Obama and Senator Clinton to make a priority of an issue that often draws little focus from politicians. But after admitting earlier this month to having an extramarital affair in 2006, Mr. Edwards has been out of the spotlight.

“Nobody will be asking him for a quote, but it will get a lot of attention,” Mr. Bernstein said. He said Mr. Obama had proposed several policies to address poverty, including an expansion in the Earned Income Tax Credit and an increase in the minimum wage. Still, he acknowledged the candidates were more focused on the concerns of the middle class than those of the poor.