Two possible reasons. One, they didn't believe he was really that bad. Two, they didn't believe he had a chance of actually winning the nomination. It was probably some of both. But regarding the latter, even Hillary didn't believe Obama had a chance.
Obama had a brilliant campaign which leveraged caucus states over primary states where the Democrat party was strong, leveraged the youth volunteers in predominately white caucus states, and leveraged his race in the red state south, where a big black turnout gave the Super Tuesday primaries to him. I think Hillary actually got more primary votes nationwide than Obama.
"Why was most of the Right's focus on defeating Hillary Clinton in the primaries rather than doing everything possible to prevent this monster from gaining power?"
I bet even here on FR most of the people in in 2007 and the first half of 2008 had a paranoid fear of Hillary. Sean Hannity called his show the "Stop Hillary Express" for all of 2007 and half of 2008. The right was more concerned with Hillary's Wellesley thesis on Saul Alinsky than Obama's experience as an Alinsky acolyte.
One other thing was so little was known about Obama. He was a man without a history. That should have been a major red flag, but instead it prevented bad news. There was no dirt to dig up, because there was no place to dig.
I am still amazed that only one or two people from the time Obama was a child through Occidental and Columbia have actually been interviewed about him. I don't recall any Punahou classmates ever being interviewed. And there was one friend from Occidental, and Obama's roommate from Columbia, and one professor from Columbia interviewed.
Very little was heard from his first Chicago days, his Harvard days, his second Chicago days, his Illinois legislature days, or even his time in the Senate. He seems to be a loner of a man with no friends, or at least no friends he wants people to talk to.
And for some reason, the press never ran with the scandals (Ayers, Rezko, Wright), because they so desperately wanted a Democrat in the White House.
I remember Sean Hannity had Reverend Wright on his show in 2007, long before it ever made the mainstream media.
Not true. The truth about who and what Obama is, was there for all to see if they only bothered to look. For one thing, he never held any single job for very long. For another, when he got that first book deal, he and Michelle took off for someplace in the South Pacific (place name escapes me at the moment, but think it was Bali). They spent months there while he supposedly wrote the book. His resume is littered with similar examples that pointed the way toward the presidency we see today as the "vacations" pile up one after the other.
Obama was an avowed Marxist very early in his young adulthood, perhaps even earlier.
Reading the timeline of his years in and post college, it is extremely clear someone was funding his rise, pulling strings every step of the way. The rails were greased for him long ago.
But the Right was too busy cutting its own to ribbons while chasing 1990's ghosts. They would not listen to the few voices who tried to warn them of the danger Obama posed.