But when Democrats got a look at the 844-page measure, they discovered that their negotiators extracted more concessions than they thought possible. Those include an expansive version of the DREAM Act and subtle but meaningful tradeoffs on all the major pieces of the system, from family reunification to legalization and border security.

The compromises raise a potential stumbling block for the bill as it starts what could be an arduous process through Congress. Conservatives could balk at signing on to something that has the stamp of approval from liberal lawmakers and progressive groups. And liberals may have a hard time accepting something that Republicans may argue is a clear-cut victory for them…

“I must admit, I was impressed,” Sen. Ben Cardin (D-Md.) said Thursday after receiving a briefing with other members of the Senate Democratic Caucus. “You get a sense, and it looks like people seem to be responding very favorably.”

Sen. Chuck Schumer (D-N.Y.), a leader of the gang, emerged from the hourlong session with a bold prediction: “We will have the overwhelming majority of Democrats for the bill.”