In recent US Presidential elections, legislators typically lose to executives. Going back to 1952, this hasn't always been the case, but since 1976, whenever a legislator has opposed an executive, the executive has won. As clarification, legislators are people who develop and pass laws; listed below is an impressive array of Representatives and Senators. Executives are people who are responsible for enforcing laws and for the direction the organizations they lead take; mayors, governors, and military or business leaders fall into this category. These two jobs are different branches in our government, so a legislator running for President, the chief executive office, is an attempt at branch-hopping. (This isn't wrong - it's just an observation.)

• In 1952, Eisenhower, a military leader (executive), defeated Adlai Stevenson II, a former governor - twice.
• Kennedy was a legislator, his 1960 opponent was Nixon, whose only executive experience was as Ike's VP, so this was legislator v. legislator.
• Kennedy's VP, legislator Johnson, assumed the presidency when Kennedy was assassinated, and defeated legislator Goldwater in 1964.
• Nixon then defeated former-mayor-turned-legislator and Johnson VP Humphrey in 1968, and legislator McGovern in 1972.
• With Nixon's resignation, legislator-turned-VP Ford lost to executive Carter in 1976.
• Executive Reagan defeated executive Carter in 1980, and defeated legislator-turned-Carter-VP Mondale in 1984.
• Reagan's VP, George H. W. Bush, does not neatly fit into our categorization. He was a legislator-turned-VP, but he also served as the director of the CIA for the last year of Ford's presidency, an executive position. However he's categorized, he defeated executive Dukakis in 1988.
• In 1992, executive Clinton defeated Bush, and he also defeated legislator Dole in 1996.
• Legislator-turned-VP Gore lost to executive George W. Bush in 2000, who went on to defeat legislator Kerry in 2004.
• 2008 brought legislator v. legislator again, with Obama defeating McCain (a rare pairing of legislator for President with executive for VP).

This brings us to 2012, where legislator-turned-President Obama faces a challenge from executive Romney. Of course, presidential political patterns are made to be broken, but they remain interesting just the same. This breakdown doesn't fall neatly into one party or the other; both vacillate between nominating executives and legislators, sometimes choosing legislators over executives in the primary elections.

(And, just a quick note for Joe Biden - if Obama wins a second term, things don't look too good for you. Pure legislators-turned-VP (Ford, Mondale, Gore) have done even more poorly than legislators running for the presidency.)