The campaigns of President Barack Obama and his Republican rival, Mitt Romney, are preparing for what could be a series of legal battles over new U.S. voting laws after the Nov. 6 election – especially if the result of the presidential race is close. The campaigns and political parties are lining up lawyers for what would amount to a new wave of litigation surrounding election laws that have been approved by Republican-led legislatures in more than a dozen states since 2010. Some of the laws involve requiring voters to produce photo identification. Others curtail early-voting periods that are designed to help working-class people cast ballots if they can’t make it to the polls on Election Day. Still others have imposed strict requirements on groups that conduct voter-registration drives.