Martin, 29, won the vacant belt with a third round stoppage victory over Vyacheslav Glazkov in January and now wants a quick-fire return to action against fellow undefeated puncher Joshua.
The American is even willing to travel to the UK for the privilege of putting his title on the line for the first time against the Olympic gold medallist, who is set to headline the O2 Arena on April 9.
“I can confirm that Charles Martin is willing to fight Joshua April 9 in London,” Borao exclusively told World Boxing News on Friday.
“Charles wants to make a statement in his first defense and wanted a Wilder or Fury unification. Both are busy with mandatory and contracted fights with Povetkin and Klitschko, so Joshua is the next best thing.
“Joshua is immensely popular in the UK and a fight with Martin makes a lot of sense, I believe.”
On whether contact had been made between the two teams, Borao added: “Fighters respective promoters have spoken and we have a ton of respect for Joshua as a fighter and Eddie Hearn has done an amazing job promoting him.
“Hopefully, it can happen. If not, we have plenty of options on the table,” he pointed out.
Joshua, 26, has blitzed his way through 15 opponents, all inside the distance since turning pro in 2013 and is highly ranked with all the main governing bodies.
Should a fight fail to materialize between the pair, Joshua is already lined up for an IBF final eliminator against Carlos Takam at some point in 2016, meaning a clash with Martin is inevitable if both fighters remain undefeated.