NEW YORK -- As the crisis over Mexico's disputed presidential election continues, questions are being raised not only about the conduct of the seemingly defeated candidate, Andres Manuel Lopez Obrador, but also about Mexico's presidential system. Is "presidentialism" as practiced in Mexico part of the problem?

Felipe Calderon of the center-right ruling party, the National Action Party (PAN), currently leads in the vote count, which must be confirmed by September. The next scheduled presidential election is not until 2012, as are elections to the Senate, whose assent is needed for most legislation.

Thus Calderon and his party allies, with 41 percent of the Senate seats, can never have a majority during his six-year term, and will also have a minority in the lower chamber, where PAN holds only 43 percent of the seats, until at least 2009.