The former Bundesliga operator, 32, is believed to have been offered a multi-year deal by Victoria’s third team, who enter the competition next season.
After a bright start under his compatriot Markus Babbel, the German - whose one year deal expires in May - has lost his automatic starting spot since the arrival of dynamic duo of Kwame Yeboah and Mitchell Duke.
Baumjohann has made 17 appearances this season for two goals and three assists.
He won the Bundesliga and German Cup with Bayern Munich, played in a UEFA Champions League semi-final with Schalke, where he won the Cup for a second time.
But two ACL tears in as many years compromised his high-flying career, forcing him to dig deep to resurrect his football future.
Though he started in Saturday’s 3-2 loss to the Newcastle Jets, Baumjohann has been used off the bench in the preceding weeks.
It’s understood he is keen to maintain his presence in the A-League - most likely at another club.
The Wanderers, who are looking to bring in a marquee playmaker, are thought to be unwilling to make a counter off, thus guaranteeing his departure.
They have been eyeing off Melbourne Victory’s Kiwi kingpin Kosta Barbarouses, but are reluctant to match his salary expectations.
United, meanwhile, have already announced eight signings, with at least five more believed to have committed themselves to the new entity.
If Baumjohann signs, he will join the likes of marquee Panagiotis Kone, defenders Josh Risdon, Connor Chapman, Aaron Calver and Dylan Pierias; Olyroos midfielder Sebastian Pasquali, Polish goalkeeper Filip Kurto, rookie ex-Adelaide striker Apostolos Stamatelopoulos and Valentino Yuel from the NPL.