The Houston Rockets are reportedly pursuing a trade for Boston Celtics star Rajon Rondo before the deadline.  A holdup in the ongoing trade discussions is Houston's unwillingness to part with Chandler Parsons, Marc Stein of ESPN reports.

Houston is poised to make the biggest trade of the season if they can reach an agreement with Boston.  Rockets general manager Daryl Morey, who has a close relationship with Celtics president Danny Ainge, is making a last-minute push for Rondo ahead of Thursday's trade deadline.

"The Rockets want to acquire Boston Celtics star point guard Rajon Rondo, according to sources familiar with Houston's thinking," Stein wrote on Wednesday.  "Yet sources told ESPN.com that talks between the teams have not progressed to a serious stage because the sides can't agree on a trade framework both can embrace.

"One main stumbling block, sources said, is Boston's desire to acquire blossoming swingman Chandler Parsons in a potential Rondo deal.  But sources say the Rockets have informed the Celtics that they are not prepared to surrender Parsons as part of a Rondo package."

Rondo, a four-time All-Star, isn't necessarily being shopped, but multiple reports indicate the 27-year-old is available for the right price.  That price, however, is believed to be exorbitantly high per Celtics owner Wyc Grousbeck's insistence. 

One report indicates Boston would want at least two unprotected first-round picks.

Houston has one first-round and two second-round picks in the upcoming draft, as well as the contract for disgruntled center Omer Asik, who Boston reportedly sought to acquire in December.

The trade rumor could come to fruition because, as Stein points out, Morey has made a trade at every deadline during his seven-year stint as Houston's general manager.  Morey also has a history with Ainge, whom he worked under in the Celtics' front office.

Houston and Boston have until Thursday, Feb. 20 at 3:00 p.m. ET to complete a deal.