The Alliance won 25.4% of the national vote in the 1983 general election, compared to Labour's 27.6%. However, a mere 23 Alliance Members of Parliament (MPs) were elected, compared to Labour's 209. The SDP came second in many constituencies, including nearly 70% of the Conservative-won seats, though the bulk of Labour's defectors to the SDP in 1981 lost their seats. Due to the first past the post electoral system, this success did not translate into parliamentary seats. The SDP's support was spread out across the country, and was not concentrated in enough areas to win more seats. The split in the centre-left vote is claimed to have helped the Conservatives to win the election by a landslide.