Yesterday’s decision by the Obama administration to forestall the deportations of undocumented immigrants who don’t pose a threat do public safety is a huge, huge deal. Not just for the hundreds of thousands of undocumented immigrants who won’t be ripped away from their homes and families, but because it stands as a good example of the White House responding constructively to criticism from the left — and doing the right thing in political and policy terms as a result.

“I was pleasantly surprised by the boldness and breadth of Administration’s move,” Frank Sharry, Executive Director of the pro-immigration reform group America’s Voice, told me. The plan includes reviewing the deportation proceedings of 300,000 people already in the system, and allowing those who don’t have criminal records to stay.

Since taking office, the Obama administration has implemented a far more aggressive immigration enforcement policy than the Bush administration — deporting close to 400,000 people a year. The idea was that aggressive enforcement would clear the way for comprehensive immigration reform, a plan that didn’t take the total opposition of the Republican Party into account. Despite the administration’s stated focus on deporting undocumented immigrants who pose a threat to public safety, the vast majority of those deported were convicted of minor offenses and many had no criminal record.

Nevertheless, Republicans have ignored this reality, instead accusing the administration for months of implementing a “stealth DREAM Act” through its enforcement priorities. Republicans are likely to revive these accusations given that the administration now says it will allow some “low-priority” undocumented immigrants in the system to apply for work permits. But make no mistake: No matter what conservatives say to the contrary, this is a temporary solution. It is not “amnesty” in that it does not grant a path to citizenship — it merely offers temporary relief to a select few.

When the DREAM Act vote failed last year, immigration reform advocates were split on whether to focus on blocking anti-immigrant legislation in the House, on long term mobilization for comprehensive immigration reform, or on fighting restrictionist laws coming out of newly empowered Republican state legislatures. The decided to pressure the administration to stop deporting DREAM-eligible undocumented immigrants, many of whom had outed themselves in an attempt to put a human face on the issue of illegal immigration.

“These groups stood up and put before the country of how these policies were tearing families apart, marriages being ripped apart, parents being torn away from their kids,” says Jeffrey Parcher of the Center for Community Change. “They were very courageous on going after the president, and putting the faces and consequences of these deportations before the administration and the media.”

Although 22 Democratic Senators sent a letter to the administration requesting a formal process of “deferred action” for potential DREAM-eligible undocumented immigrants, the administration demurred, with President Obama telling immigration advocates privately and publicly that change needed to come through Congress. In his speech to the National Council of La Raza in July, the president said: “I need a dance partner here -- and the floor is empty.”

What changed?

Obama’s poll numbers among Latino voters began to slip. Both on the local and national level, immigration reform advocates upped the pressure, even protesting at the Obama administration’s headquarters in Chicago. While the debate over the administration’s aggressive enforcement policy largely occurred under the radar in the mainstream media, Obama was getting pilloried in the Spanish-language press for breaking his promises.

All the while, the administration was getting no credit from the right for its aggressive enforcement policies, even as deportations rose, the number of illegal immigrants dropped, and more resources were deployed at the border. Heading into 2012 with little in the way of progress to show on immigration reform, the administration likely felt that it had to do something to show that its immigration policy agenda was more than just mass deportation.

Of course, implementation matters. DHS said yesterday that it was committed to keeping its deportation numbers high even with the new policy. But the numbers don’t add up — there simply aren’t 400,000 dangerous undocumented criminals to deport every year. And the federal enforcement agencies have bucked their political leadership in the past, and may do so again.

“There will be an inherent tension between their enforcement goal and the implications of this policy in terms of providing relief for the communities,” Parcher says. “It’s the old Reagan thing. Trust but verify. The implications are potentially huge, but only if they follow through.”