Sprint is sending out request for proposal that evaluates LTE for its next-generation network, according to a Light Reading article.

"There's nothing that prevents us from... moving to LTE," said Kevin Packingham, senior VP of product and technology development at Sprint.  "We're doing a technology evaluation and making a decision on our core network and how we want to evolve that going forward."

Sprint has not declared its evolution path yet but this confirms that LTE may be an option. 

Sprint is the only carrier pursuing WiMax as a 4G technology. The other three, AT&T, Verizon, and T-Mobile are going the LTE route. However, Sprint's CEO Dan Hesse has said earlier that if LTE turns out to be the standard in the future, Sprint would be open to changing over to LTE.

The reason Sprint has been so aggressive with WiMax instead of LTE is that the company has a lot of the spectrum already acquired. 

Earlier Clearwire too has shown interest in LTE. However, in an interview with CNET, Clearwire CEO Bill Morrow said that Clearwire won't be deploying LTE anytime soon and definitely not before 2012. See Clearwire CEO: No LTE deployment before 2012 for more details about it.