You'd have to be pretty heartless to oppose legal status for DREAMers — people who were brought to the United States illegally when they were children.

Sen. Marco Rubio (R-Fla.) is apparently of requisite heartlessness.

Rubio declared last week that he can't support the bipartisan Development, Relief, and Education for Alien Minors (DREAM) Act that some of his Senate colleagues are desperately trying to enact to make DREAMers off-limits to the Trump administration's harsh deportation regime. Regrettably, instead of embracing compassion, he's throwing in his lot with Trump's gang of cruel restrictionists.

Now, President Trump has repeatedly assured us that he has a "big heart" and would concentrate on deporting "bad hombres" while "taking care" of DREAMers. The reality, however, is quite different.

A bit of background: President Obama created the Deferred Action Against Childhood Arrivals (DACA) program that, as its name suggests, deferred deportation proceedings against DREAMers and handed them temporary work permits. But DACA does not offer any guarantee against detention or deportation, just a postponement. Its protection can be rescinded for the slightest of infractions — even traffic violations — which is what Trump has effectively been doing.

In other words, Trump has left DACA in place but rendered it essentially toothless. Even so, 10 hardline attorneys general from red states are not satisfied. They have given Trump an ultimatum and told him he has to totally scrap the program or they'll sue, just as they did with President Obama's DAPA initiative that gave a temporary reprieve even to parents of DREAMers. If the administration obliges them — or declines to fight them in court — all 1.8 million DREAMers could eventually be deported, including the 750,000 who have DACA status.

Please remember: These are people who had no say in how they were brought to America, and who have lived in this country practically their whole lives with little to no contact with their birth land. They deserve compassion, not icy cruelty, especially since deporting just 750,000 would cost Uncle Sam $60 billion and lead to $280 billion in economic losses over the next decade.

To that end, Sens. Lindsey Graham (R-S.C.) and Dick Durbin (D-Ill.) have dusted off the DREAM Act, which would hand green cards to illegal immigrants brought to the U.S. as children so long as they (i) graduate from high school or serve in the military; (ii) pass a background check; (iii) speak English; (iv) demonstrate knowledge of U.S. history; and (v) pay a fee. About 1.5 million DREAMers are expected to qualify because they tend to be hardworking, law-abiding people who desperately want to come out of the shadows and participate fully in American life.

Even many vocal immigration hawks don't have a problem with giving these DREAMers legal status so long as it's done via legislative rather than executive action. Rush Limbaugh, who has single-handedly killed many an immigration reform bill, has conceded that "no one's gonna win by deporting a bunch of kids that we let in." Likewise, Pat Robertson, who has derided undocumented immigrants as "moochers," admits that DREAMers are not criminals. "They're teaching kindergarten, for heaven's sake," he says. "They ought to stay. They enrich our society. They bless our society, and what have we got to loose." Former House Speaker Newt Gingrich, another immigration opponent and Trump ally, counsels: "Why pick a fight over this group of people who have a lot of emotional stories to tell?" Even more to the point, polls show that 75 percent of Trump supportersTrump supporters — don't want DREAMers booted out for the sins of their parents, and actually want them legalized.

So who on Earth are the opponents of the DREAM Act?

Breitbart, the rabid online mouthpiece of immigration hawks, of course. The right-wing nationalist website is trying to kill the bill by calling it amnesty, a curse word in ultra-restrictionist circles. And then there are all the outfits that are part of the quasi-racist FAIR (Federation for American Immigration Reform) network, including the Center for Immigration Studies and NumbersUSA. Both of their leaders are vehemently opposed to any relief for DREAMers without tough border restrictions first.

And now Marco Rubio has jumped on their side.

The Florida senator has declared that he can't support the Graham-Durbin effort because it does not take into account the "reality of the situation" and guard against "unintended consequences." What reality? What unintended consequences? Apparently, Rubio fears that this law will be misinterpreted in Central America and encourage kids to show up on U.S. shores in the hopes of getting amnesty, fueling a repeat of the 2014 unaccompanied minor crisis. But the notion that amnesty — not the labor needs of the American economy or the dangerous conditions in their own countries — drives desperate foreigners to risk their lives to come to the United States is a right-wing trope with little basis in reality.

The fact is that the "unintended consequences" Rubio is concerned about are for his own political career. He was one of the Gang of Eight senators whose support for a comprehensive immigration reform bill in 2013 made him the favorite whipping boy of ultra-restrictionists in the last presidential election and no doubt (in his mind) cost him the Republican nomination. His opposition to the DREAM Act is now surely calculated to avoid giving them any reason to target him in 2020, should he decide to run again.

But going full Breitbart is unlikely to prove a winning strategy. President Trump derided Rubio as "Little Marco" during the campaign. Rubio could use the DREAM Act to stand up to Trump and ask him to produce that "big heart" he claims to have and sign the bill. Stooping to the level of the restrictionist fringe, unfortunately, would only prove Trump right about just how small Little Marco really is.