Each candidate is still on their respective tickets because the party members chose them as the party leader, and want them to run for president.
Difference is, no one in the Democratic party is asking Hillary to step down. Every Democratic party leader and national elected leader is supporting Hillary. No Democrat goes from debate to debate, nervous that Hillary might say or do something that will embarrass her or her party.
In short, Hillary’s still on the ticket because Democrats want to keep her on the ticket. If Trump drops off the ticket, it will be because Republicans do NOT want Trump to represent them anymore, or Trump decides staying in the race is not worth it. Democrats have no control over what Trump decides to do.
Righties, this is your mess and your mess only. You chose Trump. You think that the country, or the world, or the media is being unfair to Donny? Cry me a river. If you want to blame Donald’s situation on Hillary or the unfair media, go ahead, you’re just confirming the conservative culture of victimhood.