Perseveration is a term that is used in mental health settings to describe a client who focuses on a specific topic, phrase, person, or event. When a person is constantly talking about one specific topic (ie, how the CIA is after him), you would say that he is perseverating on that topic.
The word isn't only applied to what a specific person may be doing. Perseveration can also be applied to the media, in the sense that from time to time the media grabs onto a specific topic or event and covers it endlessly. For the past month, the media has perseverated on death, most specifically the deaths of Terri Schiavo and Pope John Paul II. CBS, ABC, NBC and its cable channels, Fox, CNN - all were guilty of "all Schiavo/Pope, all the time." When the media behaves in this manner, it is as if nothing else happens that is noteworthy, and so the only topic of discussion is the one that is looped endlessly.
Now it seems that Republicans and Democrats are perseverating as well. The Republican's hot-topic-of-the-moment is the "activist judge" whose evil goal is to destroy democracy (read this and this ). The President is on board, and there is a website where good citizens can go to find out what they can do. The Democrats have their lasers pointed at Tom Delay, U.S. congressmen for the 22nd district of Texas and the majority leader for the House. Democrats believe Delay was a grandstander when Terri Schiavo was waiting to die, and he has many ethics violations that should force him from the House (read this, this, and this). Of course, Mr. Delay, being the good little Republican that he is, points back at a specific activist judge.
Now don't get me wrong, these are important topics. Checks and balances are an important thing in our government, and a person with political power should have the highest standard of ethics. But there are many important issues that are facing our nation, not just whether a judge can let gays marry or if a congressman can pay his family with fundraising money.