As high-level budget talks drag on in Washington, the Medicaid program for the poor remains a prime candidate for cuts. In recent months, Republicans have criticized Medicaid for badly serving its target population. But a new study — the first of its kind in nearly four decades — finds that Medicaid is making a bigger impact than even some of its supporters may have realized. The study, being published as a working paper by the National Bureau of Economic Research, has a distinctly bipartisan flavor. Among its authors are Katherine Baicker of Harvard, who was an economic adviser to President George W. Bush, and MIT economist Jonathan Gruber, who has advised the Obama administration. Overall, researchers found that compared to people without insurance, those with Medicaid had better access to and used more healthcare; they were less likely to experience unpaid medical bills; they were more likely to report being in good health; and they were less likely to report feeling depressed.