Bolton rules out 2012 run, Giuliani says he’ll consider if party is ‘desperate’

Ahead of tonight's Republican presidential debate, one long-rumored contender announced Tuesday he is skipping the campaign while another all but ruled out a last-ditch nomination bid.

Former United Nations Ambassador John Bolton told Fox News' Greta Van Susteren he wanted to run to turn the race's focus toward national security but in the end he realized he simply couldn't win.

"It was a very difficult decision, and my view has not changed one iota that we need a much more robust discussion of national security issues as part of this presidential campaign," Bolton said.

But, the mustachioed former ambassador added, "I kept coming to the conclusion that I couldn't possibly win the nomination, and I didn't like that answer."

Meanwhile, in an appearance at the National Press Club Tuesday, former New York City Mayor Rudy Giuliani said he still hasn't made a final decision about whether he'll make a second bid for the Republican nomination. But he admitted he would have a tough time winning the nomination and suggested he'd only jump into the race if truly necessary.

"It would be difficult for me to be nominated," Giuliani said, per CNN's Ashley Killough. "We'd have to be truly desperate."

But Giuliani didn't quite say he's out of the race. Jokingly, he noted that he won the mayorship in New York City under similar "desperate" circumstances. "You know what my slogan was?" he noted. "'You can't get any worse.'"