From New Bedford, Mass. to Postville, Iowa, the federal government has been conducting raids on factories in an attempt to deport illegal immigrants.
Will the next president be able to build majorities in Congress to enact a new immigration law, after fruitless attempts in 2006 and 2007?
And what kind of balance will the president strike? Is the electorate eager for more vigorous enforcement and more deportations? Or do Americans want to offer illegal immigrants a path to become legal residents?
Why it matters
An estimated 12 million illegal immigrants live in the United States.
That illegal population, the difficulty of finding and deporting those immigrants once they’re here, and the cost to state and local governments of jailing those who commit crimes — all have implications for an array of other issues: national security, drug trafficking, job losses, and health care.
The public is divided on the issue, with some supporting amnesty, others calling for deportation, and many of the businesses that employ illegal immigrants stuck in the middle.
Both parties have wrestled with how to deal with illegal immigration legislatively, even as some activists in each party have tried to exploit the issue to make the opposing party look bad.
The GOP is divided between pro-business interests, which value the economic advantages of having a low-wage illegal immigrant work force, and some social conservatives, who fear that immigrants won't assimilate into American culture.
Conservatives are further fractured on the issue, with some on the right praising Latino immigrants for having traditional family-centered values, and others criticizing the creation of insular Spanish-speaking communities in some states.
Democrats are also torn. On one side is the party's traditional labor union base, which is concerned about job losses and lax immigration policies.
On the other side is the increasingly powerful Latino Democratic voting bloc, which supports a much more generous immigration policy.
President George W. Bush’s 2007 attempt at getting immigration reform through Congress is an accurate illustration of how contentious the issue has become.
The failed proposal would have increased border security and created a path for illegal immigrants to become naturalized.
But many in the president’s own party mocked the measure as "amnesty." A stalemate in Congress led Bush to abandon the effort.
Where the candidates stand
“Once you get past the initial rhetorical seeming difference, then there aren’t significant differences between the two candidates,” said Demetrios Papademetriou, who heads the Migration Policy Institute, a Washington-based think tank. “Both of them would agree that the whole system needs reform.”
Sen. John McCain has spent years working to reform immigration policies. In 2006, the Arizona Republican joined with Massachusetts Democrat Sen. Ted Kennedy to introduce an immigration bill that would have allowed illegal immigrants to apply for citizenship as long as they learned English and paid back taxes and fines.
Sen. , McCain's Democratic presidential rival, supported the bill.
Traditionally, McCain and Obama have tended to differ on the order in which they plan to deal with their list of immigration problems. McCain has often pointed to the priority of border security, while Obama has been reluctant to give preferences.
“The difference may be one of sequencing and how they argue the case,” Papademetriou said. “Mr. McCain now sequences things. Mr. Obama does not.”
After the failure of the McCain-Kennedy bill, and subsequent others like it, McCain said he now understood what Americans wanted.
“The lesson is they want the border secured first,” he said on NBC's "Meet the Press" in January.
Despite having suffered defeats in the past, McCain insists that immigration reform would be a priority if he wins the White House.
“It will be my top priority yesterday, today and tomorrow,” the candidate told a group of Latino officials in June. “We have to secure our borders…but we also must proceed with a temporary worker program that is verifiable and truly temporary.”
Obama has supported amnesty legislation in the past, but he appears to have more wiggle room when it comes to the issue. Perhaps because, unlike McCain, he has yet to put his name on a bill.
And recently, he's even been willing to talk about which problems he'd tackle first.
While campaigning in North Carolina on March 26, Obama spelled out his plan for immigration reform. Step one: Border security. Step two: Crack down on employers who hire illegals.
Once those two steps are completed, Obama said, the government should offer a path to citizenship for existing illegals.
But neither Obama nor McCain seems especially keen on increasing the number of deportations.
"We’re going to go and get mothers and fathers who are working, you know, for a lawn care service or working at a restaurant, we’re going to arrest them, separate them from their children, lock them up, ship them out?" Obama said skeptically.
"It would cost us billions of dollars."
And when McCain was asked about recent raids in which illegal immigrants have been arrested and deported, sometimes leaving family members behind in the United States, he said the raids were a symptom of the problem. "Of course we don't want anything done that is inhumane," he said.
How they have voted
McCain sponsored the 2006 immigration reform bill that was criticized as an attempt at providing amnesty. He also opposed an amendment that would have limited a guest-worker program to five years.
McCain voted for a measure that would allow police to question an individual about his immigration status if the police officer had probable cause to believe that he was not lawfully present in the United States.
Obama voted for his opponent's 2006 immigration reform bill. He favored the amendment that would have limited the guest-worker program to five years.
Obama opposed the measure that would have allowed police to question individuals about their immigration status.
In October 2007, Obama voted for the Dream Act, which would have provided a path to citizenship for illegals under 30. McCain skipped the vote.
The timing of immigration reform is a topic that both candidates have avoided. It is unclear if Obama or McCain will make reform an immediate priority in the early days of his administration.
Timing is crucial, as naturalization of new citizens is contentious in the months leading up to an election. If either candidate puts the issue off into the second half of his term, he could be seen as using immigration reform as a way to garner votes from newly naturalized immigrants.
“The common understanding is that those who naturalize will likely vote, more of them will vote Democrat than they will vote Republican, but it very much depends on who naturalizes them,” Papademetriou said.
With millions of people possibly gaining voting rights from immigration reform, the timing of a reform effort could prove very political.
Evolution and shifts in position
After his 2006 bill generated a backlash from the public and his own party, McCain has since said repeatedly that he will focus on border security first. He has proposed to deal with the existing illegal population only after those borders are secure.
McCain has also said that looking back on the legislation today, he would not have voted for the 2006 measure.
Obama has been consistent in his support for the three major elements of immigration reform: border security, a guest worker program, and amnesty for the 12 million illegals in the U.S.
Surprises for the new president
While the public wants border security to be the top priority for immigration reform, some say tightening the border without a solid guest worker program could add to the problem.
Irene Bloemraad, a professor of sociology at the University of California, Berkeley, said it would be a mistake for either candidate to withhold a guest worker program until the borders have been secured.
“The more money that is put on the border and the harder it is to cross the border, the more you actually increase the undocumented population in the United States,” said Bloemraad.
“Mexican migration used to be very cyclical. If you raise the cost of crossing the border, if you make it very expensive, people don’t go back.”
Bloemraad also said that providing a path to citizenship doesn’t automatically mean all illegals will be able to apply. If an amnesty bill requires immigrants to speak English but doesn’t provide the resources for them to learn the language, many illegals simply won’t apply.
The McCain-Kennedy bill did include a provision for English language assistance, but funding for the assistance would have come from charitable donations, not the government.
“In other countries like Canada and countries in Europe, the governments actually give money for things like learning English,” Bloemraad said. “There’s not that many day laborers who can just go on the Internet and do an [English] class.”