Late Tuesday, TradeSports' futures contract for GOP House control was trading at 53.8 — a 53.8% chance. TradeSports gives an 80.3% chance that Republicans will hold onto the Senate...

The prediction markets tend to do better than polls because they are able to capture "the wisdom of crowds" and consider questions a pollster wouldn't think to ask, said Don Luskin, chief investment officer at TrendMacrolytics.

When real money is at stake, those making predictions are more likely to integrate and weigh all the evidence.

This generates "a holistic view" that isn't skewed by personal bias, he said.

Republicans shouldn't be breathing easily, however. Luskin figures the markets will have much better predictive power closer to Nov. 7. He notes current readings basically signal a 50-50 contest.

What's noteworthy is that these markets suggest Republicans have revived from "a near-death experience," Luskin said. In early September, the markets gave Republicans only about a 40% chance of holding the House.