CNN) -- Democrats have usually conceded the evangelical vote during presidential elections, but Sen. Barack Obama is trying to change that by mobilizing what some call the "Christian left." As part of his outreach to evangelical voters, the presumptive Democratic presidential nominee Tuesday will tour the Eastside Community Ministry in Zanesville, Ohio, and give an address on how he plans to build what he calls a "real" partnership between faith-based organizations and the White House if he becomes president. Obama's outreach to evangelical voters has also included private summits with pastors, an effort to reach out to young evangelicals and...