The Library of Congress has just released a mass of themed web archive collections.
In terms of the USA there are over 5,000 websites covered for state, regional and presidential elections from 2000 onwards. It is possible to browse or search the database.
The web archive also has a number of other political themed collections which are of value to researchers as in many cases the resources are no longer live online. They include the following the number of sites archived is indicated by the number next to the title.
- Burma/Myanmar General Election 2015 Web Archive
- Afghanistan, Iran, Pakistan Presidential and General Elections 2017 to 2019 Web Archive 
- Pakistan Nationalisms Web Archive 
- Philippine General Election 2010 Web Archive 
- Political Islam Web Archive