The Republican Party and Republican voters are similar to the college freshman who attends their first frat party, has the time of their life getting plastered and thinking how great college is going to be, then wakes up the next morning on the front porch of a strangers house with the worst hangover they've ever had. "Where am I and what have I done" is the typical reaction. The Republican Party must do the responsible thing and correct its poor decision making.
The Republican Party should address the buyer's remorse that four out of five voters are having regarding the nomination of Donald Trump for president. It is having an affect on the party's image, and could have an impact on the Congressional races. The party should acknowledge the issue and distance themselves from him.
With the elections so close, there really is nothing the Republican Party can do except analyze why everything went wrong. Even after Trump became the Presidential candidate, they should have coached him and molded him into a candidate who would appeal to the majority of Americans. The Republic Party failed their supporters by letting Trump go about things in his own way.
The Republican party made their bed, now they get to lie in it. It is too close to the election for the Republicans to try to replace their candidate. They will pay for it later, especially with the trickle-down effects on the House and Senate, but they don't get to change their mind now.