Johnson was greatly discredited by 1968 and drags the Democratic Party down with him.
Rockefeller and Reagan had made a deal before the election that whichever one of them finished with more electoral votes would get the support of the other one.
After the election, Reagan made it known that he was supporting Rockefeller for President, and that the House should confirm his election.
Enough Democrats from the north, midwest, and west defected and cast their votes with the Republicans in the state delegations to give the House state delegation vote to Rockefeller, confirming him as the nation's 37th President.
These Democrats could not justify confirming Johnson, with only 86 electoral votes, compared to Rockefeller's 200.
Reagan becomes Secretary of State, and some of these Democrats from the House receive plum federal appointments.
Was a deal struck with these dissenting Democrats before the House vote? We'll never know.
Rockefeller/Scranton 208
Reagan/Helms 196
Johnson/Humphrey 86
Wallace/Chandler 45
McCarthy/Edwards 3