The loss of the Leaders Party's eight MPs on Wednesday means the government of Prime Minister Charlot Salwai only has a one seat majority.
Mr Kalsakau would not be drawn on how many MPs now support him, saying he is more interested in building a perfect team.
He said he could either develop a strong opposition which will support him until the election in January 2020, or push for a vote of no confidence.
"There are two options available to me at the moment. One is to either develop a destructive and perfect opposition to last me until the elections, and you'll be expecting a lot of fireworks in parliament in 2020," he said.
"The other consideration is if there is such a need to - because of the poor performance of the government - to effect change, to take over the leadership, to provide much needed service delivery to the people."
"If it appears that there is a further change in mindsets or numbers, then I certainly would proceed to file a motion of no confidence. There is a lot of occurrences in government at the moment that are seriously questionable," Mr Kalsakau said.