Although President Obama promises to make immigration reform an urgent priority in his second term, other issues are taking center stage in Washington, including the debt ceiling, gun control and a host of new Cabinet appointments that some Republicans are vowing to oppose.

The legislative and political calendar is already becoming crowded. Unless reform advocates are prepared to insist that an overhaul of immigration must be at the top of the agenda for the president and Congress, fixing the system may be sidetracked once again by diehard opponents and the need to deal with other pressing issues.

Fortunately, advocates have just received new impetus for the effort to fix the system in the form of a new report by the nonpartisan Migration Policy Institute.

The report says the government spent $18 billion on immigration enforcement in 2011 — more than all other federal law enforcement agencies combined — resulting in record levels of detentions and deportations. Customs and border enforcement, the report found, refer more cases for federal prosecution than all the Justice Department agencies combined.

At the same time, apprehensions along the border have fallen to a 40-year low — roughly 340,000, down from roughly 1.6 million in 2000, reflecting a decrease in illegal entries. Indeed, beginning in 2007 with the onset of the recession, immigration has turned into a negative flow.

All of this should set the stage for a new approach to the immigration debate. President Obama and his predecessors, including President George W. Bush, have undeniably lived up to the “enforcement first” demands of immigration opponents. Now it’s time to deal with the real problem.

The new debate should go beyond enforcement and the laudable but piecemeal attempts by Mr. Obama to tinker with the system, including his unilateral declaration of a new work permit policy that came in the middle of the presidential campaign. What is needed is a comprehensive approach that includes a practical and orderly path for legalization that can benefit some of the 11 million undocumented people living here.

Mr. Obama has made it clear that he understands his debt to the Hispanic community, whose votes helped him win reelection and who by and large want to see significant changes in the way this country deals with immigration.

Some Republicans get it, too, including Miami Rep. Mario Diaz-Balart, a key figure in bipartisan talks aimed at finding sensible compromises to rewrite the rules of immigration.

In the other chamber, Sen. Marco Rubio, who raised the immigration issue during the campaign, albeit tentatively, has not followed through. Sen. Rubio has disappointed those who believed he would take the lead on this issue.

Mr. Diaz-Balart and others like him understand that fixing immigration is only fair — and a necessary first step in allowing members of his party to compete for Hispanic political allegiance.

But that doesn’t guarantee a victory for immigration reform. Advocates have momentum coming out of the election, but support from the White House and some parts of Capitol Hill won’t last unless supporters make it clear that they aren’t willing to wait like they did during Mr. Obama’s first term, when immigration was overshadowed by the economy, healthcare reform and other issues.

The president must lead by becoming more involved in the immigration issue, and proponents must keep up the pressure for change. There won’t be a “next time” or another second term. Customarily, presidents lose much of their political clout in the later years of a second term — there’s no point in waiting until mañana.