League sources told ESPN.com that the Rockets engaged in trade talks with numerous teams once they began aggressively shopping Howard right before the start of the All-Star break.
Sources said that in recent days, the Rockets talked about potential Howard deals with a list of teams including Atlanta, Boston, Charlotte, Chicago, Dallas, Miami and, most recently, Milwaukee. Sources say Houston, however, told several teams that it wasn't prepared to trade Howard without receiving at least one frontline player and a future first-round draft pick in return.
The Rockets took a similar approach with young power forward Donatas Motiejunas and managed to extricate a first-round pick from the Detroit Pistons for Motiejunas in the one trade they did complete on deadline day.
But interested teams were unwilling to pay such a premium for Howard, at least in part because Howard, who turned 30 in December, can become a free agent July 1.
"Many teams called expressing great interest in trading for Dwight," Howard's agent, Dan Fegan, told ESPN.com on Thursday night. "The obvious stumbling block to a trade was how could a team justify giving up important assets for a player who was about to become a free agent in a few short months?
"Not surprisingly, as the deadline approached, several teams called stating they had worked out the trade parameters with Houston for a Dwight deal but were not prepared to give up their assets unless Dwight agreed to opt in to the last year of his contract and forego free agency. Dwight declined."
Howard, who reiterated he had never made any trade demands, said Thursday that he was moving forward and would focus on helping the Rockets get into the playoffs.
"It doesn't matter. I know who I am," Howard said. "I know what I have done in my career; no need to focus on anything negative. I have a great life, blessed beyond measure. Doesn't matter. People can talk as much as they want, but I know how hard I've worked to get to where I am today, and I'm grateful for that."
Fegan refused to discuss specific teams that made pitches for Howard, but sources told ESPN.com that the Bucks were one of those teams.
The Bucks and Rockets did exchange some trade proposals, sources said, but Milwaukee made it clear that it wouldn't go through with any deal for Howard unless he opted into the final season of his contract, which is scheduled to pay him $23.3 million in 2016-17.
Howard earns $22.3 million this season in the third year of his four-year, $88 million contract with the Rockets and has made it clear he intends to bypass Year 4 to return to the open market.
"It was going to have to take something significant to make us look at anything, and even then we probably wouldn't have [traded Howard]," Rockets general manager Daryl Morey told the Houston Chronicle on Thursday night.
"Part of my job is I have to explore everything."
In reference to recent reports of growing friction between Howard and James Harden, Morey told the Chronicle: "We believe in James and Dwight together."
Expounding more on the Harden/Howard pairing in an interview with The Vertical website, Morey said: "This is a group that we would be very reluctant to split up. Obviously there was a lot of interest in [Howard] -- I think there was a lot of noise about that -- but that [duo] was something we were going to be very reluctant to break up. As part of my job, I do have to listen to everything, but nothing got close and we weren't going to split that up unless it was something significant."
Howard has averaged 14.6 points, 12.0 rebounds and 1.5 blocks in 44 games this season after injuries limited him to 41 games in 2014-15.