Marco Rubio is on most short lists for the Republican vice presidential nomination.  The principal objection many conservatives have is whether Rubio is constitutionally eligible.  How should we view this issue?  At the outset, we need to dispose of the idea that the Constitution contemplates political parties nominating candidates to run for president or vice president.  It does not.    

Both president and vice president are elected by a special constitutional body, the Electoral College.  The members of that college are under no obligation to vote for any person to be president or vice president.  If a Perry-Rubio ticket swept all fifty states, the Electoral College could instead, quite properly, elect Al Franken and Maxine Waters to be president and vice president.  In recent presidential elections, some electors have shown their constitutional independence.  In 1972, Nixon "carried" Virginia, and yet one of that state's electors voted for John Hospers.  In 1960, all the popularly elected delegates in Mississippi were "unpledged."  

We are used to thinking in terms of "popular vote" for "candidates" of "parties."  Constitutionally, these terms mean nothing at all.  Electors are chosen by the method established by the state legislature.  Until 1824, those electors were not chosen by the people at all, so if you want a good trivia question, ask someone for the popular vote in the 1820 presidential election (there is none.)  But look at the 1824 election and the birth of "popular vote." Six states -- South Carolina, Georgia, Louisiana, Delaware, New York and Vermont -- had no popular vote for presidential electors at all.  South Carolina continued that practice right up to the Civil War.

After the Electoral College selects whomever a majority of its members want to be president and vice president, the role of Congress is very limited.  In case of a tie in the Electoral College or if no person receives a majority of the votes in that body, then the House elects the president and the Senate elects the vice president.  The House can impeach a sitting president and the Senate can remove that president after a trial, but those powers must find misconduct while in office.  Article I, Section 1 also provides a means to remove a president if there is an "Inability to discharge the Powers and Duties of said Office."  The 25^th Amendment, which sets up this congressional power, is clearly intended to cover sickness or mental instability and, crucially, it provides for the president to resume the powers of his office when he is sound.

Congress, then, has no role in determining who is eligible to be president.  Does the federal judiciary have a role, then?  The scariest remark that I have read by conservatives is that federal courts have some role in judging the qualifications of someone chosen by the Electoral College.  Federal courts' jursidiction, including the Supreme Court (except for a few narrow powers of original jurisdiction), are only what Congress confers upon the courts.  Beyond that, the Supreme Court could not even exist in our nation until the president and Congress are elected:  when Washington was president and the first Congress was elected, there was no federal judiciary at all, and there could not have been until someone was elected president.

So how is this issued resolved?  Consider how the Constitution deals with the eligibility of persons to be elected to the House or the Senate.  Article I, Section V provides that the "Each House shall be the judge of its own Returns, Elections and Qualifications of its Members."  What does that mean?  If a 23 year old is elected to the House of Representatives then once the House determines he is qualified for the office, that constitutional issue is resolved. 

Presidential electors ought not to choose as president anyone who is not eligible for that office, but once it has elected a president, the constitutional issue is resolved...unless we want to invent extra-constitutional powers in the federal judiciary so that it can determine who may be president and who may not.  If the Electoral College acts irresponsibly, then the constitutional remedy is through state legislatures who may change completely how these electors are chosen. 

There is a final check, of course, and that is the integrity of the person assuming the presidency or vice presidency.  The oath of office implicitly includes a promise to adhere to Article II, Section 1.  No ineligible person can honorably take that oath of office.  I realize how unsatisfactory this seems.  The transformation of the Electoral College into slavish ciphers and not serious officials and the rise of political parties and the imaginary "popular vote" has contorted the process of electing presidents into something very different from what the Founding Fathers intended. 

What could be done to change this?  State legislatures could begin to choose the presidential electors again, restoring states' rights and ending voter fraud.  We could amend the Constitution to provide for announced candidacy and a preliminary determination of eligibility by some body.  Or we can, as conservatives quite properly have done, make the qualifications issue a real political issue.  But unless we really want to open the Pandora's Box of Supreme Court meddling, we are stuck with what the members of the precise instrument of choosing a president -- the Electoral College -- does.