Scott Walker announces and other headlines

Scott Walker releases his presidential campaign announcement. (Milwaukee Journal Sentinel)

Hillary Clinton economic plan to chart center-left course. (Wall Street Journal)

Grieving Joe Biden weighs his political future. (New York Times)

Eurozone leaders reach deal to resolve Greek debt crisis. (BBC)

Deal in Iran nuclear talks 'imminent.' (Washington Post) 

Mexican drug cartel leader tunnels out of prison. (NBC News)

Post-retirement David Letterman has a special Top 10 List for Donald Trump. (Talking Points Memo)

New photos of Pluto's moon shows a chasm deeper than the Grand Canyon. (Washington Post)

What are you reading this morning? Let us know in the comments, please.