We in America are fortunate, although 'pride goeth before the fall' and boasting is not a good idea. There are some commendable democracies elsewhere, among them Canada, of course, and various countries in Europe and elsewhere.
I am not so sure that America has been a great democracy for long and has some problems even today. I recall, for example, how Woodrow Wilson labeled World War I a 'war for save democracy' while he instituted the worst segregation policies into Washington, DC. FD Roosevelt was somewhat better on black-white relations, but far from perfect, and it was under him that Japanese-Americans were involuntarily 'relocated'. The election of Obama, whether or not we agree with his policies, is a healthy sign that the USA seems to have made considerable progress when it comes to race relations.
As for 'Catholic principles' - hm! - I visited Spain during the Franco days, and he claimed to have put Catholic principles into practice. But was it a democracy? No way. He did not permit either political or religious freedom in any true sense. I recall studying Thomas Aquinas years ago. He stated that heresy was more serious than political dissent, as it imperiled the immortal soul, and he recommended that heretics be delivered to civil authorities to be executed. Not very democratic, I would say. It was the 'Syllabus of Errors' of Pope PIus IX (1870?), in which he strongly condemns democracy, that still scares Protestants and others.
There is a certain irony in that most Catholics in Congress today are Democrats who are pro-choice when it comes to government policy. That includes such top brass as Pelosi, Kennedy, Kerry, and on and on. Interesting contradiction? Perhaps it shows that the Church has lost its influence in the political arena. The most pro-life politicians would seem to be evangelicals from the South.
Catholics, like all other Americans, should keep well-informed on the issues and vote their consciences. It's almost impossible to find a candidate with whom one can agree 100%. But we need to do our best. How moved I was this past Thursday when I reheard the Gettysburg Address with its emphasis on "of the people, by the people and for the people." Lincoln doesn't seem to have been a traditional Christian but he certainly was a truly great statesman.