Late Monday, No.2 Republican Senator John Cornyn put tight time constraints on the normally slow-moving Senate.
"It's this week or not at all," Cornyn said of the need for quick Senate action. Speaking to reporters, he warned that the debate had to be "wrapped up" by Thursday, before next week's congressional recess.
Democratic Senator Dick Durbin, Cornyn's counterpart, told reporters he hoped a combination of the Senate's 49 Democrats and independents, coupled with 11 Republicans, could get behind a bill, propelling it to passage.
Cornyn said tepid support from Republicans was a recipe for failure: "If they think... they can cobble together a handful of Republicans to go along with a majority of Democrats and somehow get it past the House and get the president to sign it, I think that's a pipe dream."
Under an order issued last year by Republican President Donald Trump, the Dreamers could be deported after March 5. That deadline looms behind the rare Senate debate, in which no single bill was to be the centerpiece and a range of ideas was in play.
By forcing the deadline on Congress with his September order, Trump drove a wedge between Democrats and Republicans on an emotionally charged issue. The rhetoric around the debate was running red-hot even before it got started.
"This week we will see the horrific vision of the White House and extremist Republicans on full display... their vision is nothing short of white supremacy," Greisa Martinez Rosas, a Dreamer activist told reporters in a teleconference.
On the other side, the group Advocates for Victims of Illegal Alien Crime said in a press release: "The reality is that American families are the ones suffering the most - their children killed - by illegal alien crime."
Bridging the ugly divide between factions in the immigration debate, one that Trump himself has widened with his inflammatory statements, will be a challenge for Congress.