Smaller parties have refused to prop up the group which remains the largest party despite a devastating defeat at last week’s election.
Instead, these parties have chosen to support the Conservatives who have a third of the council seats, according the Labour group.
The Tories have promised opposition parties the opportunity to work together for the “genuine good” of the whole borough by creating a more open and transparent council.
In a statement, the Labour group said: “Labour is still the largest party on Bolton Council, but despite initial constructive talks with the minor parties, it has now been confirmed to us that those minor parties have chosen instead to support Conservative power in our borough despite the Conservative Party obtaining fewer votes than Labour.
“The Conservatives have been out of power in Bolton for 40 years and there is clearly a reason why Bolton people have continually rejected them. This year’s election was no different – the Conservatives did not win a mandate.”
Labour lost seven seats at this year’s local elections, throwing the council into no overall control.
The Conservatives only made one overall gain as new hyper-local parties picked up four seats on the night.
But Tory leader David Greenhalgh defended his party’s performance.
He said: “These were the worst elections for Bolton Labour probably in the history of the metropolitan borough.
“Where there was a viable alternative to Bolton Labour, opposition parties flourished, and the residents of this borough sent a clear message that they preferred an alternative.
“I’m afraid it is Bolton Labour that residents have lost confidence in, and their refusal to accept that, is unbelievable.”
The Lib Dem group doubled in size last week, ending up with six councillors, which gives them significant sway in negotiations between parties, together with UKIP’s group of three.
Farnworth and Kearsley First and Horwich and Blackrod First have seven councillors between them while Independent councillor Debbie Newall is set to rejoin the Labour Party, which would give the group 24 seats.
The Bolton News understands that councillors from all parties except for Labour will agree to appoint a Conservative leader to the council on May 22.
Labour acknowledged that it suffered setbacks in the election but blamed people’s lost confidence in politics on Brexit and government cuts.
The Labour group added: “We pledge to listen and do our utmost to rebuild our relationship with the people of Bolton.
“As the only opposition party in Bolton we will act in a constructive manner to ensure that the most vulnerable people in our society continue to be protected from cuts administered by the Conservatives.
“In addition, we will work hard to ensure that Labour’s £1.2 billion regeneration plans for Bolton and the townships, now beginning to happen, continue to go forward.”
A more detailed announcement is expected tomorrow.