republican, publican

Republican or republican describes a representative form of government--
The king banished him for spreading republican ideas.
"The United States shall guarantee to every State in this Union a Republican Form of Government..."

Republican is also a noun ( thing or idea ), meaning a person who believes in a representative form of government--
Although he was born with a title, his principles made him a republican.
He was a republican, much to the dismay of his monarchist parents.

Republican is also the name ( a proper noun when used this way, and always capitalized ) of one of the major political parties in the United States--
Are you registered as a Republican or a Democrat, or are you unaffiliated?
You have to register as a Republican if you want to vote in the Republican primary.

Publican or publican means a form of tax collector, who bought the rights to collect the taxes, and then went calling on people to get the money they owed--
The publican was a familiar sight to some of the first settlers in America.
The ancient Romans used a publican to collect the taxes.

Publican or publican, informally, means an innkeeper--
The publican says that it's closing time.
Ask the publican for another round of beers.

Now that you know that, you can say--
"The king's soldiers were aware that the publican was a republican sympathizer."