Republicans are "in a demographic death spiral" and will fail in their effort to win the presidency if the party blocks an immigration overhaul, a leading GOP senator said Sunday. Sen. Lindsey Graham, the South Carolina Republican who helped write a bipartisan immigration bill under debate in the Senate, said conservatives who are trying to block the measure will doom the party and all but guarantee a Democrat will remain in the White House after 2016's election. A Democrat also involved in developing the proposal, Sen. Robert Menendez of New Jersey, went a step further and predicted "there'll never be...