Complex sentence: As a member of the SDP's national steering committee he advised on the selection of SDP candidates for the forthcoming general election and lead negotiations with the Liberal Party concerning the sharing out of constituency candidacies between the two centrist parties.
Split into simpler sentences: As a member of the SDP's national steering committee he assumed a prominent role in the selection of SDP candidates for the forthcoming general election. He also assumed a prominent role in negotiations with the Liberal Party concerning the sharing out of constituency candidacies between the two centrist parties.