Al Qaeda ragime change

If you think about Al Qaeda has caused a regime change in Spain faster the the US/UK invasion of Iraq.

I wonder if something like this is possible here. If there was to be a big terrorist attack near to an election, could it force people to vote for the oposition because they feel the present government has brought this on the people?

I know a lot of people believe that an attack in the USA would more likely re-install the present government.