In July, Barack Obama’s visit to Germany was promoted with a poster that highlighted his speech in Berlin.

The design is obviously similar to those produced in the 1920s and 1930s by the Bauhaus movement, which boasted strong sans-serif typefaces and used diagonal lines and lettering to increase the dynamism of the composition. After World War I, the ideas of the Bauhaus school influenced a generation of graphic designers, including those in the political domain. An example of such a poster is one by Nico Schrier (in the lower-right box) in which a man is calling his “comrades” to “vote Red” (the color of The Netherlands' Social Democratic Workers’ Party) in the 1933 election.

Typography was taught at the Bauhaus as early as 1923, and instructor László Moholy-Nagy stated that type "must be communication in its most intense form. The emphasis must be on absolute clarity." This is evident in the sans-serif lettering in the two posters shown here.

Both posters also featured one dominant image. This works to focus the viewer's attention on a key visual, limiting competing elements, which could distract. 

[Thanks to Laura Larrimore for alerting me to the Obama poster.]