Most of the GOPe oppose Trump but they don't want to come out and say it because they want to keep their majority in Congress. But by having a third party candidate with just enough appeal to throw the election to the House they can tell the voters you must vote for the GOP down ticket so that a Republican House decides who the next president is and not a Democrat House.
The GOPe would trade a Hilliary Presidency if they can retain control of Congress....as well as many GOP voters who are used to picking the lesser of two evils....
it wouldn’t be the “new” House which would decide the presidency, it would be the current House which serves until Jan. 2017
the Electoral College meets in early Dec.
The House would have until Inauguration Day, Jan. 20 2017 to settle on a President, or else the following procedure takes place:
http://www.archives.gov/federal-register/electoral-college/faq.html#no270