WASHINGTON — The White House says President Barack Obama is a Christian who prays daily.White House spokesman Bill Burton made the remark Thursday, hours after a poll showed 18 percent of Americans think Obama is Muslim, up from 11 percent who thought so last year. A third think he is Christian, and 4 in 10 say they do not know Obama's religion.Burton told reporters aboard Air Force One that most Americans care more about the economy and wars in Iraq and Afghanistan and, he says, are "not reading a lot of news about what religion the president is."Burton said: "The president is obviously a Christian. He prays every day."The poll was conducted by the Pew Research Center and its affiliate Pew Forum on Religion & Public Life.