MEXICO CITY - This month, Mexico's Felipe Calderón celebrates his second anniversary as president. Calderón took office in December 2006 under adverse circumstances. Elected with 35% of the vote, he lacked a majority in Congress, and the opposition refused to acknowledge his victory. He has also had to govern in a persistently difficult environment: a lame-duck president next door in the United States, a severe economic downturn, and the legacy of corruption, negligence, and complicity handed down by his predecessors since 1968, when Mexico's old one-party political system began to crumble.