Search engine advertising -- paying to place small ads alongside Google's search results -- isn't new, but advocacy groups are using it in increasingly sophisticated ways, as NationalJournal.com's Amy Harder details in a new story.

A new ad campaign by conservative group FreedomWorks, which targets Blue Dog Democrats who voted for the stimulus bill, demonstrates how advertisers are taking a page from the presidential campaigns of Barack Obama and John McCain, both of whom used search engine advertising to cheaply and effectively reach voters during the race.