"I think they would lose the Senate today," Caddell told Fox News's Stuart Varney on Monday.
"You wouldn't have thought so in October, when the shutdown occurred, before Obamacare took effect and the Republicans were shooting themselves in the foot," he said. "But the Obamacare thing gets worse and worse. Perception is reality. And this reality is pretty grim..."
For Democrats, the "real problem" with Obamacare is that "people lost insurance, are losing it, are not finding the insurance they want," Caddell said.
"The one lie of the year -- maybe of the decade -- if you like your health insurance, you can keep it, if you like your doctor, you can keep it, that doesn't go away. That needs to be drilled over and over for the Republicans.
"The Democrats are in terror of this because prices are going up, costs are going up."
Caddell called Obamacare an "ostrich issue" for Democrats, who may tell themselves it's not really as bad as it is. "The truth is, it's very bad," Caddell said.
"Now, let me tell you how bad it is. The Wall Street Journal poll, which came out last week...which showed that people who are uninsured, who ought to be the champions of Obamacare because they're going to get coverage, and a lot of it will be subsidized, they have gone from 34 percent thinking it was bad in October in one month to 50 percent.
"The numbers of people who think it was a bad idea have increased. This is affecting people because, as I said, perception is reality."
Varney asked Caddell, if the election were held today, would Democrats lose the Senate?
"I think they would lose the Senate today," Caddell said.
Caddell said Republicans' biggest problem is the party's failure to offer an alternative -- "a program saying, here's what we will do."
"That's a missing piece they need," he added.