Campaigns Turning Focus to Borders If you're focused on the presidential campaign, get ready for the politics of immigration. President Obama set the stage on Friday by announcing that he would unilaterally stop enforcing deportations against many illegal immigrants who came to the United States as children. But immigration was already set to be the topic of the week on the campaign trail. OBAMA IN MEXICO: Mr. Obama left on Sunday for Los Cabos, Mexico, for the G-20 summit meeting of the world's major economies. Topics other than immigration are likely to dominate the two-day meeting: the economic crisis in Europe, a meeting with President Vladimir V. Putin of Russia, and the political and military crises in Egypt and Syria. But the location of Mr. Obama's trip provides the backdrop for a discussion of immigration between Mexico and the United States. And by announcing his new deportation policy just days before arriving, Mr. Obama all but ensured that it will come up in discussions with other leaders and with reporters. What he says in Mexico will immediately echo on the campaign trail, where Mitt Romney has already criticized Mr. Obama's new policy. But on Sunday, Mr. Romney dodged the question of whether he would repeal it if he got into the White House next year. "What the president did - he should have worked on this years ago," Mr. Romney said on "Face the Nation" on CBS. If he felt seriously about this, he should have taken action when he had a Democrat House and Senate, but he didn't. He saves these sort of things until four and a half months before the general election. THE COURT: Any day now, the Supreme Court is expected to announce its decision on the constitutionality of an Arizona law that expanded the powers of police officers in the state to enforce immigration laws. The decision could have far-reaching implications for illegal immigrants. A ruling upholding the law could be seen as a green light for other states to follow suit. If the court strikes the law down, it may help immigration activists who say Arizona went too far. On the campaign trail, either decision could supercharge the issue. Mr. Romney must contend with conservative supporters who do not want him to embrace amnesty or comprehensive immigration reform. Mr. Obama faces Hispanic voters already suspicious of his commitment to the issue. For months, both candidates have largely sidestepped the issue (though they have each released ads in Spanish). A Supreme Court decision will be hard to ignore. DUELING SPEECHES: But perhaps the most direct engagement on the issue of immigration is likely to come at the end of the week, when Mr. Obama and Mr. Romney are both scheduled to deliver remarks to the National Association of Latino Elected and Appointed Officials annual conference in Orlando, Fla. Mr. Romney is scheduled to go first, addressing the group on Thursday. It will be an opportunity him to expand - or not - on his response to Mr. Obama's new immigration policy. It will be a tricky moment for Mr. Romney, who appears to be trailing Mr. Obama badly among Hispanic voters. Several top aides have said he must find ways to narrow that gap. But doing so too aggressively could undermine his support among conservatives. For Mr. Obama, who is to speak on Friday, the appearance is likely to be less contentious because of his new policy on deportations. Some Latino supporters have expressed frustration with the president for not pushing harder to achieve a comprehensive immigration overhaul that would provide a pathway to citizenship for many of the illegal immigrants already in the country. That may still be an undercurrent on Friday. But many Hispanic activists have cheered his new policy, making it more likely that he will be received warmly at the event.