Portillo Moments in your country

[Former President tack50]

Because of the electoral system, it's almost impossible to get a "Portillo moment". The closest you can get is the 1982 election.

The ruling party, UCD, torn apart by infighting went from 34.8% of the vote and 168 seats to 6.8% and 12 (a loss of 156 seats!). This meant that PM Calvo Sotelo (not running for reelection as PM but still wanting to be an MP), lost his seat in Madrid (got only 1 seat there, he was number 2).

In fact the party leader Landelino Lavilla came really close to losing his seat as well. The party got 3.3% of the vote in Madrid. If they had dropped below the 3% threshold the party leader would have lost his seat.

Not sure if it even qualifies as everyone expected UCD to get decimated but still, the PM not getting back his seat I guess qualifies.

The only other I can think of is the 2004 general election: Everyone expected PP to lose some seats compared to their great result in 2000 but still win the election comfortably. However good campaigning by the opposition plus the terrible government reacction to the 2004 Madrid bombings meant that they ended up losing the election by 4.5 points. (polls before the attacks predicted a 4 point PP win, after the attack illegal Andorran polls only had it at a tie)

[Former President tack50]

While not fully official yet, you could argue the recient Andalusian election was a Portillo moment. No one expected the left to lose its majority for the first time since the end of the dictatorship. Let alone with the help of a far right party and let alone by a comfortable margin (50-59)

In fact, this was probably the most unexpected election result since at the very least the 2004 general election, but at least 2004 saw a terrorist attack days before the election. No one could have predicted Andalucia.