The immigration debate is threatening to split the Republican Party, pitting those who focus mainly on presidential elections against those who care mostly about congressional races.Strategists say that if Republicans are to win presidential elections, which they’ve been losing lately, partly because of dismal support from Hispanic voters, they must soften their rhetoric about illegal immigrants and embrace some version of "immigration reform.”But granting illegal residents a path to citizenship, which critics call "amnesty,” is deeply unpopular in many House Republicans’ districts.President Barack Obama wants such a pathway. So do some prominent GOP lawmakers who are seeking a way out of their party’s jam.The plans differ on when and how citizenship might occur, with border security a central issue. Resolving these differences may determine whether a major law is enacted in the coming months.Some GOP strategists fear they will lose either way.If by the next election Latino voters think Republicans opposed and possibly blocked a comprehensive immigration overhaul, they might turn against the party in even bigger numbers.On the other hand, converting millions of illegal Hispanic residents into citizens might produce large numbers of new voters who will lean Democratic for years."This is a perilous debate that Republicans have entered into,” said John Ullyot, a Republican consultant and a former Senate aide.Agencies