U.S. Sens. Elizabeth Warren and Edward Markey have voted against a bill aimed at reopening federal agencies through Feb. 8.
The two Massachusetts Democrats were among 18 senators who opposed the deal.
Warren pointed to a lack of an agreement to protect an estimated 800,000 "Dreamers," who were brought to the country as children and are now here illegally.
Markey also cited the young immigrants and the lack of sufficient aid for Puerto Rico and communities devastated by the opioid crisis for his opposition.
Senate Minority Leader Chuck Schumer said Senate Majority Leader Mitch McConnell agreed to begin debating an immigration bill by Feb. 8.
Warren said the country needs new laws, not new promises.
New Hampshire's Democratic senators, meanwhile, say they worked with a group of more than 20 senators to reach a bipartisan agreement to reopen the federal government.
Jeanne Shaheen and Maggie Hassan released a joint statement Monday saying that the negotiations once again have affirmed there's substantial common ground between both parties on critical priorities, such as strengthening the military; combating the opioid crisis; continuing the Children's Health Insurance Program; and protecting immigrant "Dreamers," more than 700,000 younger immigrants brought into the country as children.
President Donald Trump signed a bill reopening the government late Monday, ending a 69-hour display of partisan dysfunction after Democrats reluctantly voted to temporarily pay for resumed operations.