Anthony Joshua's camp have so far had "no response" from Deontay Wilder's representatives despite renewed efforts to set up a heavyweight unification fight, according to head of Matchroom Sport Barry Hearn.
WBA-WBO-IBF champion Joshua has repeatedly stated that WBC titlist Wilder is his No. 1 target for his next fight, which is due to take place at Wembley Stadium, London on April 13.
Negotiations between the pair collapsed last year after the WBA grew tired of the protracted talks, ordering Joshua to take on Russian mandatory challenger Alexander Povetkin instead. Wilder, meanwhile, went on to face former heavyweight title holder Tyson Fury in a memorable draw in Los Angeles last month.
According to Hearn, Joshua's camp have continued to push for the Wilder fight, but they have been left frustrated with the lack of response from the American's people.
"We would desperately love to fight Deontay Wilder in Wembley on April 13th," Hearn told Love Sports Radio.
"Unfortunately [I have] to report that so far despite three, four emails, dozens of phone calls, we haven't had one response from Deontay Wilder's team.
"So sooner or later, you take the hint that maybe they don't want us that bad. But then they're also planning a Tyson Fury rematch."
If neither Wilder nor Fury are available for April, Joshua is likely to turn to London rival Dillian Whyte -- who defeated Dereck Chisora for a second time in December.
Joshua entered the ring to speak with Whyte following his 11th-round knockout victory, telling the Brixton boxer he "knows how the list goes", insinuating he was second choice to Wilder.