From the excerpt of the article that you posted, I couldn’t tell whether State Sen. Thompson was a Democrat or a Republican. Then I remembered that if he were a Republican, I would have been told that in the first paragraph.
Looking at the link to the AP article, it was not until the 12th (!) paragraph that my suspicions were confirmed. Mr. Thompson is a Democrat.
(Sigh). Is there an AP Style Manual that dictates how these things are reported?