[Serious] Which american politicians (both left & right) are legitimate contenders to contend the primaries to run for the next presidency?

From wiki:

Democrats formally exploring a candidacy
* Martin O'Malley, Governor of Maryland 2007–2015; Mayor of Baltimore 1999–2007; formed a PAC
* Jim Webb, U.S. Senator from Virginia 2007–2013; U.S. Secretary of the Navy 1987–1988; formed an exploratory committee

Democrats publicly expressed interest
* Joe Biden, Vice President of the United States since 2009; U.S. Senator from Delaware 1973–2009; presidential candidate in 1988 and 2008
* Hillary Rodham Clinton, U.S. Secretary of State 2009–2013; U.S. Senator from New York 2001–2009; presidential candidate in 2008
* Bernie Sanders, Independent U.S. Senator from Vermont since 2007; Independent U.S. Representative from Vermont 1991–2007
* Paul Strauss, Shadow Senator from Washington, D.C. since 1997

Republicans formally exploring a candidacy
* Jeb Bush, Governor of Florida 1999–2007; formed a PAC
* Ben Carson, author and retired Director of Pediatric Neurosurgery at Johns Hopkins Hospital; formed an exploratory committee.
* Chris Christie, Governor of New Jersey since 2010; formed a PAC
* Lindsey Graham, U.S. Senator from South Carolina since 2003; U.S. Representative from South Carolina 1995–2003; formed an exploratory committee
* George Pataki, Governor of New York 1995–2006; formed a PAC
* Rick Perry, Governor of Texas 2000-2015, Lieutenant Governor of Texas 1999–2000; presidential candidate in 2012; formed a PAC
* Scott Walker, Governor of Wisconsin since 2011; formed a 527 organization

Republicans publicly expressed interest
* John R. Bolton, U.S. Ambassador to the United Nations 2005–2006; Under Secretary of State for Arms Control and International Security Affairs 2001–2005
* Ted Cruz, U.S. Senator from Texas since 2013; Solicitor General of Texas 2003–2008
* Bob Ehrlich, Governor of Maryland 2003–2007; U.S. Representative from Maryland 1995–2003
* Carly Fiorina, former business executive and nominee for the U.S. Senate from California in 2010
* Jim Gilmore, Governor of Virginia 1998–2002; Chairman of the Republican National Committee 2001–2002; presidential candidate in 2008
* Mike Huckabee, Governor of Arkansas 1996–2007; presidential candidate in 2008
* Bobby Jindal, Governor of Louisiana since 2008; U.S. Representative from Louisiana 2005–2008
* John Kasich, Governor of Ohio since 2011; U.S. Representative from Ohio 1983–2001
* Peter King, U.S. Representative from New York since 1993
* Sarah Palin, Governor of Alaska 2006–2009; 2008 vice-presidential nominee
* Rand Paul, U.S. Senator from Kentucky since 2011
* Mike Pence, Governor of Indiana since 2013; U.S. Representative from Indiana 2001–2013
* Marco Rubio, U.S. Senator from Florida since 2011
* Rick Santorum, U.S. Senator from Pennsylvania 1995–2007; U.S. Representative from Pennsylvania 1991–1995; presidential candidate in 2012
* Donald Trump, business magnate and television personality from New York

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