The Dutch Labour party PvdA and left-wing green party GroenLinks have agreed to act as a single block in the senate after the March provincial elections.

GroenLinks senate leader Paul Rosenmöller and the PvdA’s Mei Li Vos presented their list of candidates to the public on Thursday, and outlined their plans to merge into a single group once the new upper house is sworn in.

The two parties, which have hinted at a possible full-scale merger in the past, say they now plan to seize the initiative in the upper house of parliament, where the coalition has no majority now and is very unlikely to have after the vote.

The provincial elections take place on March 15 and the results are used to determine the composition of the upper house. The two parties will appear separately on the ballot boxes but will campaign together and merge into one after the senate has been chosen on May 30.

The current coalition controls 32 of the 75 seats in the senate and if they lose more, as the polls indicate they will, either the right or the left will be able to exercise more control over government policy.

‘A very strong left-wing block is crucial to steer this country in the other direction,’  GroenLinks leader Jesse Klaver said at the gathering.

The support of the senate is needed to get controversial legislation onto the statute books.