Rock, meet hard place.

Via TPM:

The health insurance industry is planning to warn members of Congress that extending Obamacare’s open enrollment period, which a group of Democratic senators have begun to urge the White House to do, could have a disastrous effects on insurance premiums.

The proposal to extend the open enrollment period, which has been endorsed by 10 Democratic senators, is a reaction to the well-documented problems with in its opening month. With many people having trouble applying for insurance through the website, and the administration setting a Nov. 30 deadline for the site to be fully functional, the senators say people need more time to sign up for coverage. The enrollment period is scheduled to end March 31. The senators haven’t asked for a specific new end date yet.

But expect to start hearing a significant amount of pushback from the industry, with a message focused on the fact that insurance premiums could skyrocket in 2015 if the enrollment period is extended.

“We are focused on educating lawmakers and the broader policy community about why the individual mandate and defined open enrollment periods are essential to achieving broad participation in the marketplaces,” Robert Zirkelbach, spokesman for America’s Health Insurance Plans, a major industry lobbying group, told TPM. “Without these enrollment incentives, many young, healthy people may wait to purchase coverage until they need it, driving up premiums for everyone else.”

The problem, according to the industry, is that an extended enrollment period could skew their calculations for 2015 premiums. Here’s why.

Right now, insurers need to submit 2015 rates to the U.S. Department of Health and Human Services between April 1 and April 30, 2014. If the enrollment period ends in March, as currently scheduled, insurers will know exactly what their customer base looks like as they make projections about their 2015 rates.