WASHINGTON (AP) — Austere "fiscal cliff" tax increases and federal spending cuts set for the end of the year would send the economy back into recession and cause a spike in the jobless rate to 9.1 percent by next fall, congressional budget analysts said Thursday.

The tax and spending changes, which a lame-duck session of Congress will dig into next week, would cut the federal deficit by $503 billion through next September, said the Congressional Budget Office report. But the adjustments also would cause the economy to shrink by 0.5 percent next year.

The report, updating an analysis from last May, comes as a newly re-elected President Barack Obama and Congress seek ways to avert or at least ease possible damage from the scheduled changes. All sides are promising cooperation, but many difficult decisions await and the politics of raising tax revenue and cutting federal benefits programs is exceedingly tricky.