During the first coalition government led by Chancellor Angela Merkel from 2005-2009, he served as the CDU/CSU parliamentary group’s coordinator for energy issues and as deputy spokesperson for economic affairs.

From November 2015, he was a member of an informal German-Russian working group on energy cooperation, convening parliamentarians of both the German Bundestag and the Russian State Duma as well as business representatives from both countries.

[5] In the negotiations to form a coalition government following the 2009 federal elections, Pfeiffer was part of the CDU/CSU delegation in the working group on economic affairs and energy policy, led by Karl-Theodor zu Guttenberg and Rainer Brüderle.

[8] During the eurozone crisis, Pfeiffer supported Germany’s stance that it would oppose any plan to introduce euro bonds, calling them “poison.”[9] On a 2011 trip to Tajikistan, he expressed support for the Rogun Dam project, calling "the best project for the development of the region.“[10] When EADS and its American partner Northrop Grumman in 2010 cited unfair competition for abandoning their joint bid for a $35 billion contract to build tanker jets for the US military, Pfeiffer publicly called the move "a scandalous, unacceptable act.“ [11] In a parliamentary debate over the government’s decision on the sale of more than 200 model 2A7+ Leopard tanks to Saudi Arabia in 2011, Pfeiffer reasoned that it is in Germany's interest "to offer our employees in the defense industry long-term prospects.

"[12] In a 2015 interview with DPA news agency, he held that Germany must do everything possible – including arms exports – to support Saudi Arabia and similar states, arguing that these countries would help to stabilize the "powder keg" in the Middle East.