party more to the left. But, internal divisions continue, and in June 1978, a group of 42 PSD MPs release the "Unpostponable Options" manifesto where they attack Sá Carneiro and reaffirm the Social Democratic path with the candidacy to the Socialist International. Sá Carneiro returns to the leadership in the 1978 July party congress and 37 PSD MPs leave definitely the party and form the Independent Social Democratic Action (ASDI), which will merge with the PS a few years later. |- style="background-color:#E9E9E9" ! align="center" colspan=2 style="width: 60px"|Candidate ! align="center" style="width: 50px"|Votes ! align="center" style="width: 50px"|% |- |bgcolor=| | align=left | Francisco Sá Carneiro | align=center | | align=right | 100.0 |- |- style="background-color:#E9E9E9" | colspan=2 style="text-align:left;" | Turnout | align=right | | align=center | |- | colspan="4" align=left|Source: |} A few months after the congress that reinstated Sá Carneiro in the party's leadership, the PSD, CDS and PPM reach an agreement to form the Democratic Alliance, in order to contest the following elections. Electoral system The Assembly of the Republic has 250 members elected to four-year terms. The total number of MPs was reduced to 250 from the previous 263, elected in 1976. Governments do not require absolute majority support of the Assembly to hold office, as even if the number of opposers of government is larger than that of the supporters, the number of opposers still needs to be equal or greater than 126 (absolute majority) for both the Government's Programme to be rejected or for a motion of no confidence to be approved. The number of seats assigned to each district depends on the district magnitude. The use of the d'Hondt method makes for a higher effective threshold than certain other allocation methods such as the Hare quota or Sainte-Laguë method, which are more generous to small parties. For these elections, and compared with the 1976 elections, the MPs distributed by districts were the following: Parties The table below lists the parties represented in the Assembly of the Republic during the first half of the 1st legislature (1976–1980), as this election was a national by-election, and that also contested the elections: Campaign period Party slogans National summary of votes and seats |- | colspan=12| |- ! rowspan="2" colspan=3 style="background-color:#E9E9E9" align=left|Parties ! rowspan="2" style="background-color:#E9E9E9" align=right|Votes ! rowspan="2" style="background-color:#E9E9E9" align=right|% ! rowspan="2" style="background-color:#E9E9E9" align=right|± ! colspan="5" style="background-color:#E9E9E9" align="center"|Seats ! rowspan="2" style="background-color:#E9E9E9;text-align:right;" |MPs %/votes % |- style="background-color:#E9E9E9" ! style="background-color:#E9E9E9;text-align=center|1976 ! style="background-color:#E9E9E9;text-align=center|1979