"Bradley Manning revealed information that helped put an end to the Iraq wars, and he exposed abuses that the world needed to know about," Valen told Norwegian media on Wednesday.
"Edward Snowden has revealed the magnitude of surveillance that we are subjected to in the name of the 'war on terror'," the Socialistisk Venstreparti MP added.
Former CIA contractor Snowden has already been nominated for the prize by Swedish sociology professor Stefan Svallfors, who remained unavailable for comment when contacted by The Local last week.
It is also not the first time Manning, who shared war documents with WikiLeaks, has been nominated for the high-profile accolade. Northern Irish peace activist and former prize winner Maread Corrigan-Maguire had put his name forward previously.
Valen added that he considered both Manning and Snowden to be politically persecuted by their home country, the US.
"The Genève convention gives everyone the right to say no to following orders when it contradicts their own conscience," Valen told the Adresseavisen newspaper.