On many questions, President Barack Obama's approach is full speed ahead. On immigration reform, he prefers to take one step at a time. There really is no alternative.

Immigration is politically vexed because it splits both parties and scrambles the usual ideological alignments. And there is no clear majority.

Roughly one-third of Americans strongly favor granting illegal immigrants a way to become citizens, while another third is strongly opposed. But there is an ambivalent middle that knows the status quo is unsustainable and wants a comprehensive solution yet is also upset about the government's failure to stop illegal immigration.

The Obama administration has particular worries of its own. Obama won election with overwhelming support from Latino voters who helped him carry such swing states as New Mexico, Colorado and Nevada. Latino political leaders are appropriately insistent that the president keep his promise to fix immigration and end a system that, in Obama's words, "keeps those undocumented workers in the shadows."

But the president's lieutenants are aware that Obama also won in swing states where there is less sympathy for a path to legalization (Indiana, North Carolina and Ohio), and they do not want to throw immigration reform into an already combustible legislative mix. So Obama has thus been sending two signals simultaneously: Yes we can, but not quite yet.

On April 9, a front-page headline in the New York Times read: "Obama to push immigration bill as one priority." The story spoke of Obama's plans "to begin addressing the country's immigration system this year."

But note that word "begin." That's different from legislating anytime soon, as Obama made clear at his news conference last week. He said all the right things about the urgency of change. "We can't continue with a broken immigration system," he argued. Yet his answer lacked the fierce urgency of now. "We want to move this process," he said, and spoke of the importance of "building confidence." And then he kicked responsibility over to Congress. "Ultimately," he said, "I don't have control of the legislative calendar."

There is much fascination with the role of White House Chief of Staff Rahm Emanuel in crafting the administration's response. As a Democratic House leader, he was cautious on immigration reform, but he has emerged as a supporter of action – eventually. Emanuel is candid in saying his angle of vision from the White House is different from the view he needed to take as an adviser to Democrats from highly competitive districts on the politics of the issue.

While noting that his own voting record was sympathetic to comprehensive immigration reform, Emanuel observed in an interview that many of his electorally vulnerable Democratic colleagues hailed from areas in which such a position would be unpopular.

"My job then was to give them the best political advice I could, given the districts they were representing," he said. "My job now is to see this issue from a national perspective and from the president's perspective." And Emanuel was impressed with the Latino political mobilization in 2008.

Yet Emanuel and Obama know that most of those same Democrats still represent competitive seats and continue to worry about the costs of a vote for immigration reform. That's why the administration has settled on a strategy of slowly building consensus rather than moving fast.

Latino Democrats have sent a strong signal to the business lobbies. They are saying that until comprehensive reform passes, they will withhold their votes for temporary fixes to raise immigration ceilings for groups of workers sought by particular industries. They hope to pressure business to pressure Republicans to toss more votes immigration reform's way.

The success of immigration reformers will depend upon winning over those in the ambivalent middle.

The core argument for reform must be that the presence of so many illegal migrants without any enforceable rights undermines the rights of everyone else. The real message that a path to citizenship will send is that all long-term residents of our country should be able to assume their responsibilities as Americans.

Moving us in that direction is not about doing favors for illegal immigrants. It's about strengthening the American community. Obama needs to use the time he is buying himself to make that case.