President Obama reached out to crucial young voters here and in Chapel Hill, N.C., on Tuesday with a promise to keep college affordable, in the first two of three campus appearances in battleground states this week spotlighting this key voting group. Speaking to capacity crowds at the University of North Carolina's flagship campus and later in the day at the University of Colorado, Obama made his case that congressional leaders must take action before July to prevent interest rates on federal student loans from doubling. On Wednesday, the president will give a similar address at the University of Iowa. "College education is one of the best investments America can make for our future," Obama said in Chapel Hill. "This is important for all of us. We can't price most Americans out of a college education. We can't make higher education a luxury. It's an economic imperative. Every American should be able to afford it. So that's why I'm here....