Bipartisan deal ignores safeguards for "dreamers" a key Democrat demand.
US Senate leaders have reached a two-year budget deal to raise government spending by almost $300 billion.
It comes on the eve of a deadline to avert another government shutdown.
The bill is expected to clear the Senate but is likely to face opposition in the House of Representatives.
House Democratic leader Nancy Pelosi spoke out against it in a marathon 8-hour speech, a House record, vowing to oppose it for not including protections for young immigrants who entered the US illegally as children.
On Capital Hill as the deal was being made protesters were making the same demands.
If Democrats do not get a promise to advance legislation to protect the young so-called Dreamers, the budget deal might not be in time to avert a second government shutdown this year.