On the hottest flash point in the debate, Arizona's new law targeting illegal immigrants, Mr. Obama said the rules are "unenforceable" for local police. But he didn't give any indication when the administration will file an expected lawsuit seeking to block the new law, which takes effect at the end of this month. ~ Advocates on both sides of the issue say they don't expect Congress to tackle the issue before the elections, both because of the already-crowded legislative schedule and because there is no clear consensus on how to proceed.