Senate Democratic leader Chuck Schumer acknowledged Tuesday night that he has no guarantee that Senate Republicans will allow a vote on immigration in the next two weeks, an agreement he'd touted as the reason Democrats voted to end the government shutdown.

Schumer announced on Monday that most Democrats had agreed to support a procedural measure to end the funding impasse, which closed government operations over the weekend, in exchange for Senate Republican leader Mitch McConnell's promise of a vote to extend the Deferred Action for Childhood Arrivals program, or DACA, by Feb. 8.

The deal gives Republicans "17 days to prevent the Dreamers from being deported," Schumer said Monday, using advocates' word to describe undocumented immigrants brought to the United States as children.

The deal divided Democrats, some of whom accused Schumer of having "caved in" to McConnell. And after a day of protests by DACA supporters outside his Washington office and his home in New York, Schumer said Tuesday night on MSNBC's "The Rachel Maddow Show": "Is there a guarantee that McConnell keeps his word? No. But we're going to keep his feet to the fire."

Let our news meet your inbox. The news and stories that matters, delivered weekday mornings. This site is protected by recaptcha

Related: The government shutdown is over but the immigration fight has just begun

After Schumer’s appearance on MSNBC, Trump Tuesday night called Schumer "Cryin' Chuck Schumer" on Twitter and said the Senate minority leader "fully understands, especially after his humiliating defeat, that if there is no Wall, there is no DACA."

Schumer argued on the cable program that the deal was the best he could do given Republicans' control of the White House and both houses of Congress.

Related: Democrats, Trump both blamed for government shutdown, poll finds

"We're doing everything we can. But what people have to understand is we don't have a magic wand," he said. "We have a chance in February. Do not give up."

Echoing the concerns of DACA supporters and even some Senate colleagues, Kamala Harris of California, one of several Senate Democrats who voted against re-opening the government, contended that McConnell "did not make a commitment."

Related: Immigration activists renew fight for Dreamer deal

But Schumer said Tuesday night that continuing the shutdown wouldn't have solved anything and would only have hurt the Dreamers' cause. But "now we have a chance," he said.

Schumer said the math worked this way: A DACA bill has the support of all 47 Senate Democrats and the two independents who vote with the party, as well as of "six or seven Republicans — so we need only four or five more."

"We've advanced the cause," he said, adding, "we have to be smart and thoughtful and careful about how we advance the cause," he said.