So what exactly IS Sen. John Thune going to do with the $5 million he has in the bank despite no credible challenger? I asked him about that on today's conference call with the South Dakota press.

Thune said he always assumes he's going to have an opponent, which is fair. He also pointed out that his last two races — in which, of course, Thune was challenging incumbents — enormous sums of money were spent against him.

"I've been through two very hard-hitting, very expensive campaigns. I've had in two Senate races $40 million spent against me," Thune said. "You're always preparing for that scenario. We will continue to prepare."

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But if he doesn't get a serious challenger, Thune said he's going to spread the wealth.

"If I weren't to have a campaign — or a campaign like the kind I've had in the last couple of elections, I would do my best to help other candidates, both in South Dakota and around the country," Thune said. "But I will do that under any circumstances. My expectation, of course is that we will have an opponent. At some point, it will be necessary to put some of these dollars we've raised through the course of these last few years to work."