This poll doesn't show that American Catholics are overwhelmingly Democratic and support outrageous liberal causes. It shows that most American Catholics aren't even Catholic.
The past voting patterns of Catholics in presidential elections back to 1952 show overwhelming support for the dimocrat nominee for president.
But Rome herself treats such as members, thus who are you to exclude them? Was Teddy K a RC? How did the pope treat him?
If you filter out of the poll anyone who doesn't engage in a modicum of Catholic practice (only include those who attend Mass weekly, for example), the numbers change dramatically.
Somewhat (^ refers to most recent above source):
34% of weekly Mass attending Catholics are Democrats, and an additional 19% are not affiliated with a party but lean toward the Democrats (53% identifying or leaning as Democrats). 28% of weekly attenders are Republicans and an additional 17% lean toward being a Republican (43 percent identifying or leaning as Republicans). Thus Democrats have a 10% point edge among weekly attendees, Catholics who attend Mass less than weekly are even more likely to be a Democrat rather than a Republican. http://cara.georgetown.edu/NewsandPress/PressReleases/pr061808.pdf
Exit polls in 2008 reported that weekly churchgoing Catholics voted for John McCain over Barack Obama, by just 50 percent to 49 percent. Weekly Protestant church attendees voted for McCain over Barack Obama 66 to 32 percent. http://www.catholicnewsagency.com/news/churchgoing_catholics_chose_mccain_over_obama/
In the 2012 election (preliminary exit-poll analysis), white Evangelicals (23% of the electorate) voted 79%/20% Romney/Obama; Protestants overall (53% of the electorate) voted 57%/42%; black Protestants (9% of the electorate) and other Christian voted 5%/95%; Catholics overall (25% of the electorate) voted 48%/50%; white Catholics (18% of the electorate) voted 59%/40%; and Hispanic Catholics (5% of the electorate) voted 21%/75% Romney/Obama http://www.pewforum.org/Politics-and-Elections/How-the-Faithful-Voted-2012-Preliminary-Exit-Poll-Analysis.aspx
Weekly Church attendees (28% of the electorate) voted 57%/39% Romney/Obama; more than weekly (14% of the electorate) voted 63%/36% and “never” attendees (17% of the electorate) were at 34%/62% Romney/Obama. ^
A Catholic study reported that the percentage of U.S. adult Catholics who say they attended Mass once a week or more (i.e., those attending every week) was 24% in 2012. http://cara.georgetown.edu/caraservices/requestedchurchstats.html
54 percent of Catholics who came of age before Vatican Two (10 percent of Catholics today) attend Mass weekly, compared to 23 percent of millennial Catholics, those born from 1979 to 1987. http://blogs.thearda.com/trend/featured/counting-catholics-church-of-immigrants-poised-for-growth/
40% Roman Catholics vs. 41% Non-R.C. see abortion as "morally acceptable"; Sex between unmarried couples: 67% vs. 57%; Baby out of wedlock: 61% vs. 52%; Homosexual relations: 54% vs. 45%; Gambling: 72% vs. 59% http://www.gallup.com/poll/117154/Catholics-Similar-Mainstream-Abortion-Stem-Cells.aspx
Committed Roman Catholics (church attendance weekly or almost) versus Non-R.C. faithful church goers (see the below as as morally acceptable): Abortion: 24% of R.C. vs. 19% Non-R.C.; Sex between unmarried couples: 53% vs. 30%; Baby out of wedlock: 48% vs. 29%; Homosexual relations: 44% vs. 21%; Gambling: 67% vs. 40%; Divorce: 63 vs. 46% ^
64% of white evangelical Protestants [blacks make up 6% of all evangelicals] believe abortion should be illegal in all or most cases, as do 52% of Hispanic Catholics, and 41% of white Catholics, and 39% of black Protestants, and 31% of white mainline Protestants. http://www.pewforum.org/2013/01/16/public-opinion-on-abortion-slideshow/
31% of faithful Catholics (those who attend church weekly, 2004) say abortion should be legal either in "many" or in "all" cases.. 2004, The Gallup Organization Gallup Survey for Catholics Speak Out: 802 Catholics, May 1992, MOE ± 4%;
26 percent of Catholics (2007) polled strongly agree with the Church's unequivocal position on abortion Catholic World Report; survey of 1,000 Catholic Americans by Roper Center for Public Opinion Research at the University of Connecticut; http://www.adoremus.org/397-Roper.html
46 percent of Catholics who say they attend mass weekly accept Church teaching on abortion; 43 percent accept the all-male priesthood; and 30 percent see contraception as morally wrong. ^
Among Catholics who attend services regularly (weekly or more), 31% say there should be no legal recognition for homosexual relationships (marriage or civil unions), with 26% favoring allowing gay and lesbian people to marry, versus 43% of Catholics who attend once or twice a month, and 59% of Catholics who attend a few times a year or less favoring allowance of homosexual marriage. ^
27% of Catholics who attend church services regularly say their clergy speak about the issue of homosexuality, with 63% of this group saying the messages they hear are negative. ^