No argument can be made about who made Trump the Republican nominee. 
The Republican Party has complete responsibility for that.
But the GOP fought him at every turn. Or are you suggesting that by trying to do so with incorrect strategy, and therefore failing, they have "complete responsibility" for his nomination? I think that's a bit harsh. Arguably you have more of a case to pin the blame specifically on his individual opponents who wouldn't bow out of the race to rally together to defeat him. And even then it's tough to give them 100% of the blame since there were other factors in play.
So let me get this straight. The American voters are not responsible for electing Trump because they were really voting against Hillary. The Republican Party is not responsible for nominating Trump because their leadership fought against his nomination. The Republican voters are not responsible for nominating Trump because a majority of them voted for someone else.
IOW, in this great democracy, no one is responsible for electing the President of the United States?

By the Republican Party, I mean every person who identifies as a Republican and voted for Trump as their nominee. And every member who agreed to support the eventual nominee, whomever it was. Sure, the leadership didn't want Trump to be the nominee, but after he won by their rules, they supported him. As did those Republicans who supported him once he won the nomination, whether they personally voted for him or not.
None of these people had to support him. They
chose to. They have complete responsibility.
It's time for the "Party of Personal Responsibility" to own up to their personal responsibility:
Those who voted for Donald Trump for President are partly responsible for him being elected President.
Those who voted to nominate Donald Trump are partly responsible for him becoming the nominee.
Your vote counts, whether you like it or not.
Everyone who ever cast a vote for this man
chose to vote for this man. This is the man you wanted as President. This is the man you help elect. Take responsibility for it.