Mass production of Apple’s rumored 12.9-inch iPad Pro has reportedly been pushed back to early 2015. The reason: Manufacturers can’t keep up with demand for the company’s new iPhones.

Production of the larger iPads was originally slated for December, according to suppliers talking to the Wall Street Journal on Thursday. But Apple’s larger iPhones, particularly the 5.5-inch iPhone 6 Plus, have remained the company's priority.

Production of the iPhone 6 Plus has remained “unsatisfactory,” partially due to low yields of the 5.5-inch displays used in the smartphone.

“It would be challenging for display makers to split resources and spend a few months to ramp up production for a new larger-screen iPad now,” an unnamed supplier source told the Wall Street Journal.

Hon Hai Precision Industry Co., better known by its trade name Foxconn, already has 200,000 workers focused on building just the new iPhones and its components. But the company is reportedly still hiring workers in an attempt to keep up with demand.

Apple sold more than 10 million iPhone 6 units in its opening weekend in 10 countries, according to the company. Since then, it has expanded the smartphone’s rollout to over 20 more countries and plans to launch the iPhone 6 in China on Oct. 17. The company expects to have the smartphone available in 115 countries by the end of 2014.

“While our team managed the manufacturing ramp better than ever before, we could have sold many more iPhones with greater supply, and we are working hard to fill orders as quickly as possible,” Apple CEO Tim Cook said in September.

Since then demand for the iPhone 6 hasn’t subsided by much, with the iPhone 6 still seeing seven- to 10-days until shipment times and the iPhone 6 Plus seeing three- to four-week until shipment estimates from Apple’s Online Store.

The Cupertino, California-based tech giant is expected to announce a number of new devices next week at its Oct. 16 event, including an iPad Air 2 featuring Touch ID and an overdue update to the Mac Mini.