Who's running and who could run in 2016?

Published On: Nov 08 2012 10:41:49 AM CST   Updated On: May 30 2015 11:05:49 AM CDT

Former Maryland Gov. Martin O'Malley announced his candidacy for president on May 30, 2015. Check out other formally announced or potential 2016 candidates.

Rick Santorum
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Photo by Alex Wong/Getty Images

Rick Santorum, the former Pennsylvania senator who mounted an unexpectedly strong bid for the Republican nomination in 2012, is making another bid for the White House. Santorum formally launched his campaign May 27 in Pennsylvania.

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