Watch this brief video for help understanding and avoiding plagiarism:
Copying and pasting, rendered both easy and potentially tempting by the wealth of the information available via the Internet, also constitutes plagiarism. If you copy a passage electronically from an online source, you must place it in quotations and cite its source.
Common knowledge consists of facts and sayings that are well known by a large number of people or information that is included in multiple sources.
Because these are generally known facts, they are considered common knowledge and do not, therefore, need to be cited. You must, however, document facts that are not well known and ideas that interpret facts.
The idea that "Bush's relationship with Congress has hindered family leave legislation" is not a fact, but an interpretation. Consequently, you need to cite your source.