I would add taxes to the list . A lot of the current partisanship started with the first Bush . He ran on a no new taxes pledge but then the economy changed and Democrats refused to allow him to make the cuts needed . So he worked with Democrats and compromised to raise taxes . This directly led to him losing reelection because he lost a lot of Republican votes for working with Democrats but gained no Democratic votes for working with them . Republicans took the message from voters to heart and realized they had to count on far right voters instead of moderate left voters they used to be able to count on . This led to a hard line on taxes in the Republican party and the mess we are in today and is why Republicans refuse to compromise with Democrats .