Merely being a registered Democrat?  No, I don't think so.  You aren't giving them any money, or necessarily supporting them by merely being registered.  Depending on what state you live in, by being registered a Democrat, you are just choosing which primary you want to vote in.

In terms of supporting a Democratic candidate, I think it would strongly depend on their stances on certain issues.  However, these days, it is almost impossible to find a Democrat (or a Republican, for that matter) whom a traditional Catholic could support with a clear conscience.

Make a list of all the issues that the Democratic Party enthusiastically approves of and ask if that belief and practice is acceptable from a Traditional Catholic position.

First, the D's are overwhelmingly and enthusiastically in favor of abortion rights.  They even approve of government funding of abortion.

Second, the D's are in favor of racial hatred mongering and dividing people by race and pitting one group against the other for political gain.  They also support gαy marriage and all sorts of deviancies in the pursuit of political power.  They don't support these deviancies for the sake of freedom because the D's are full square behind mormon polygamy.  

Third, the D's change their position depending on how it will benefit them as a party so they adhere to a belief system that is similar to shifting sand.

Fourth, the D's are as full on against the establishment of Christ the King as is humanly possible.  

There is a lot more but I'm not really enthusiastic in making the list  

R's are guilty too but the question asked was pertaining to the D's.

I do not think, in good conscience, that a Traditional Catholic could embrace or even join the Democratic party.  

Call it petty or whatever you like. It's grammatically correct.

Democrat Party is the grammatically correct term for the Democratic Party. The Party is not "democratic", and proper nouns like "Democrat" are not properly converted into adjectives by adding "ic" as a suffix. It is not the "Republicanic Party," or the "Libertarianic Party", or a "Smith-ic Wedding." Predictably, many Democrats dislike the term, perhaps because they prefer the false illusion that their party is somehow more "democratic" than other parties.

Do you know that the ENDA law passed the senate that protects
ɧoɱosɛҳųαƖs and gives sɛҳuąƖ deviants special protection Federal
Status. and protections.
sɛҳuąƖ orientation, there are 65 classes of sɛҳuąƖ deviates and
perversions given special protection by Federal Law if it passes
the congress.
I like to give some examples, but I may cause me to sin, and
others to sin. I suggest that you do your own research.
This law had overwhelming support of Democrats and
Republicans including such conservative Senators as Orin
Hatch of Utah.
The only religious person that actively opposed this proposed
law is Rev. Ted Pike, a protestant minister.  Not one word from
the Catholic Bishops.

Make a list of all the issues that the Democratic Party enthusiastically approves of and ask if that belief and practice is acceptable from a Traditional Catholic position.

First, the D's are overwhelmingly and enthusiastically in favor of abortion rights.  They even approve of government funding of abortion.

Second, the D's are in favor of racial hatred mongering and dividing people by race and pitting one group against the other for political gain.  They also support gαy marriage and all sorts of deviancies in the pursuit of political power.  They don't support these deviancies for the sake of freedom because the D's are full square behind mormon polygamy.  

Third, the D's change their position depending on how it will benefit them as a party so they adhere to a belief system that is similar to shifting sand.

Fourth, the D's are as full on against the establishment of Christ the King as is humanly possible.  

There is a lot more but I'm not really enthusiastic in making the list  

R's are guilty too but the question asked was pertaining to the D's.

I do not think, in good conscience, that a Traditional Catholic could embrace or even join the Democratic party.  

I agree. No Catholic should be part of the dems at all. You will be counted as a supporter of their evils even if you don't vote that way.

Republicans are just as bad in various ways. People think being conservative is a "good" thing but that's been perverted to a neo con which overwhelmingly supportive of the zionists and their wars.

Both parties will bow to their same master, so not too much difference. Just different enough to hook people into believing that the political system cares for its people.

I would suggest anyone to change to independent. So you are not part of either or any direct party that supports evil. Additionally independents are listened to more because they know they have to earn those votes. Both parties assume people will vote party lines.