Wallin, chair of the Swedish People's Party, recently admitted that he blocked the closure of the Tammisaari-based Dragsvik garrison, while six other army bases are slated to be shut down to save money.
Wallin stressed that his advice had merely been on the constitutional right of Swedish speakers to receive training in their mother tongue, rather than a politically motivated intervention.
Government and opposition parties are nevertheless looking to bring Wallin to account. On Wednesday Wallin apologised to SDP ministers for failing to communicate properly during the decision-making process.
Jutta Urpilainen, the Finance Minister and SDP chair, said that Wallin should have informed the Foreign and Security policy committee about his advice to the defence forces on the re-organisation. She was satisfied with Wallin's apology, and will now press for the matter to be looked at again by the Foreign and Security committee.
Critics also say Wallin misled parliament by giving the defence staff advice to protect Dragsvik, but telling MPs the decision was made on purely military grounds.
The opposition plans to bring a vote of confidence in Wallin on Thursday. The Centre party, the Finns party and the splinter group of the Left Alliance united behind the vote, which will measure MPs backing for Wallin.