In 2008 Republican primaries, the second place finisher was Mitt Romney. Do you think he would have been a "stronger viable candidate" against Obama?I said that in 2008 that McCain was nominated on the GOP ticket by crossover Liberal Democrats, cheating Americans from a stronger viable candidate.
I don't remember any organized campaign promoting crossover voting by Democrats. On the other hand, Rush Limbaugh was very vocal about his "Operation Chaos", where he urged Republicans to crossover and vote for Hillary.
"...Rush Limbaugh, the nation's top-rated talk radio host, was urging Republicans in Texas and Ohio to skip their party's primary on March 4 and instead cast a vote for Hillary Clinton in order to prolong the fight between her and Barack Obama. And that Tuesday, as media in both states reported, thousands of Republicans did just what Limbaugh and others had suggested -- they changed parties to vote for Clinton."