Conservative and Liberal Democrat groups in Preston will make up the official opposition to the ruling Labour group.
The two parties both won nine seats each in the city council’s local election on Friday.
It meant there was initially uncertainty over which group would fill the role of the opposition party.
Newly-elected councillors met on Friday after the election count to discuss the matter.
Coun John Potter, of the Lib Dem group, said: “Everyone was shattered on Friday evening but we did get to discuss the legal position.
“Both Sue and I will be leaders of the opposition parties. Negotiations are continuing.
“We have got to finalise various things such as sorting out where we are going to sit in the chamber, for example.
“Some of the bigger things that we need to discuss include who chairs the audit committee and who chairs the overview and scrutiny committee.
“We have got an idea of what we want and it’s also about what the Conservatives want.
“It was a nice meeting on Friday. It’s all got to be sorted out with officers. I’m sure we will come up with a decent solution.”
Negotiations currently taking place between the parties to determine seats on committees will be formally agreed at Council on Wednesday, May 15.
Preston’s Labour group won 30 seats at the local elections giving the party a clear majority.