I haven’t downloaded the Oslo Terrorist’s manifesto and I don’t plan to but I’ve seen this bit quoted in a couple of places (p.1266):

’God Bless America!

We are calling for the impeachment of ALL Senators and Representatives who have voted, or are planning to vote, to expand the control of government. Republican/Democrat/Independent… no matter. We determine their guilt or innocence based on their voting record.

Additionally, we are calling for President Barrack Obama’s Impeachment for actually saying he was a Marxist, as well as not being able to provide proof of American citizenship.

We are calling for all Conservative Members of The House of Representatives to bring all leftist voting members up for impeachment under the guise that they are voting in accordance with Marxists beliefs in order to expand government control over every facet of our lives. Because it is unlikely that Congress will impeach itself, it is our sole purpose to have these leftists labeled Socialist/Marxists so that their constituency can see them for what they truly are and fail to re-elect them in the future. Any damage done to this nation should be squarely placed on their shoulders and worn for life. These men and women are a disgrace to their offices, and should therefore be labeled and removed. We know it sounds old fashion, but folks… we can no longer afford to be lenient in the description of those that are harming America. Call a spade a spade.

So Far… AIM has Identified the following Senators: (AGAIN… We DO NOT determine association with Marxists beliefs according to party affiliation, only voting record. Additionally, this list is incomplete and growing. If you have someone you believe should be on it, please let us know. Currently we are looking for more Republicans that deserve the label “Marxist.”)

ALABAMA:
…

The part after “God Bless America!” seems to be ripped verbatim from this Facebook group:
AIM - Americans for the Impeachment of Marxists

Apparently, at the very least, Breivik was a fan of theirs.