A new analysis of the Obamacare marketplaces shows a cluster of midwestern and southern states are losing especially large numbers of insurers, as companies around the country struggle to stay profitable issuing policies in the healthcare exchanges.

In the majority of counties in Missouri, Illinois, Indiana, Ohio and Georgia, consumers will have two fewer insurers to buy plans from in the online marketplaces set up under President Obama's healthcare law, according to data compiled for the Wall Street Journal by the Kaiser Family Foundation.

Most counties in Nebraska, Oklahoma, Arkansas, Louisiana, Mississippi, Alabama, Tennessee, Pennsylvania and Kentucky will lose one insurer from the marketplace. There are also big, widespread insurer exits in Oregon and Arizona, the data show.

A majority of enrollees, an estimated 62 percent, will still be able to choose from among three insurers in the marketplaces during the upcoming enrollment season. But that's still fewer than during the last signup season, when 85 percent of consumers had at least three options.

And while just 2 percent of Obamacare shoppers had just one plan to chose from last year, an estimated 19 percent will have just one choice in 2017, according to the Kaiser analysis.

Republicans in the most affected states are seizing upon the analysis as proof that their long dire predictions about the 2010 Affordable Care Act are coming true. Sen. Roy Blunt, R-Mo., slammed Obama for promising his health reform would improve competition among insurers and offer consumers more options.

"Obamacare has been a disaster for Missourians, and it's about to get even worse," Blunt said in a statement Monday. "Premiums are set to increase by double digits in some areas, deductibles are sky high and the vast majority of our state could have only one Obamacare exchange option next year."

Missouri is especially affected by a decrease in competition, as nearly every county in the state is losing at least two marketplace insurers.