There's another thread on this, but these popups are probably being loaded by "adware" that's running on your machine like a virus, not by anything from this site. These adware assholes have developed "drive-by downloads" that will install their servers on your machine without your permission or knowledge, just by visiting a site. They often attach to your browser (and sometimes other software), they put themselves into your system startup, and some go to great lengths to make themselves hard to remove.
Many of them "eavesdrop" on the URLs that your browser is viewing and try to pop up ads for a competitor's site. That sounds like what's happening here: Whoever bought the "Save US Healthcare" ads targeted several "liberal" site URLs.
SpyBot Search & Destroy (freeware) will usually remove this things, unless you've got something brand new. You can download it here:
http://download.com.com/3000-2144-10194058.html?tag=lst-0-1We need to bust these sleazy f-wads by exposing them to the media. People hate this kind of underhanded shit, maybe even more than spam, and they might be interested to know that the Repugs are using it. If you run SpyBot, it will report any adware servers that it finds. If we can definitely pin this down to adware and someone can provide the name of the adware service that's being used, we might be able to raise a major stink.