WASHINGTON — As they prepare for a critical pre-election legislative stretch, Congressional Republican leaders have all but abandoned a broad overhaul of immigration laws and instead will concentrate on national security issues they believe play to their political strength. With Congress reconvening Tuesday after an August break, Republicans in the House and Senate say they will focus on Pentagon and domestic security spending bills, port security legislation and measures that would authorize the administration’s terror surveillance program and create military tribunals to try terror suspects. ‘We Republicans believe that we have no choice in the war against terror and the only way to do it is to continue to take them head-on whether it is in Iraq or elsewhere,’ said Representative John A. Boehner of Ohio, the majority leader. A final decision on what do about immigration policy awaits a meeting this week of senior Republicans. But key lawmakers and aides who set the Congressional agenda say they now believe it would be politically risky to try to advance an immigration measure that would showcase party divisions and need to be completed in the 19 days Congress is scheduled to meet before breaking for the election. […]