The club are still waiting on final permission from their Lithuanian owners to sign off on a £2.5m deal that will see millionaire businesswoman Ann Budge take control.
The 66-year-old, who reportedly made £40m from her IT firm in 2005, will only complete the deal once creditors from the club's bankrupt majority shareholder UBIG ratify their agreement to hand over their shares to administrator BIDO.
But Locke admitted that he is becoming increasingly concerned that this deal will not go through and insisted that the next month will be crucial.
"As a football club Hearts are still not out of the woods yet," Locke said.
"The deal could collapse - but I pray that does not happen. The next month could be crucial in terms of the club surviving.
"If all goes to plan and things go well then we can start to rebuild the team on the playing side.
"The club is awaiting positive news from Lithuania but we know we have to rebuild again.
"I'm trying to look at the positive side of things. We're hoping Ann will come in and take the side forward.
"But at the back of my mind there is still a lingering doubt about the events in Lithuania."
While BDO continue to fight to push this deal through the Jambos boss knows that if his side fail to beat Dundee United on Friday night they face relegation on their own turf by city rivals Hibernian a week on Sunday.
But despite this Locke remains adamant that the biggest fight for survival remains off the pitch.
"I'm not bothered about the Hibs game now. We've got United first and that's all I'm focusing on," Locke said.
"I've not thought about what will go through my head if we're relegated.
"We know it's looking impossible to survive now but we've got a young group of players and the future at Hearst will be bright.
"It's important that we don't forget the biggest battle is off the field because things have gone pretty quiet on that front.
"Without a doubt it is the most crucial period in the club's history."