A political action committee affiliated with Charles and David Koch has announced its intention to focus energy on supporting a specific type of Democratic candidate, with the goal of protecting them against upstart primary challengers such as those seen in the 2018 election, according to CNBC.

The Koch Brothers PAC Americans For Prosperity said it will support incumbent candidates from any party who show a willingness to take principled political stands and seek to unite with others—protecting them from more extreme primary challengers who might seek to oust them.