Council politics has been rocked by a shock defection.
Lowton East Coun Edward Houlton has quit the Community Action Party to join the Conservatives.
The move makes his new party the biggest numerical group outside ruling Labour and means the Tories become official opposition at the council for the first time in almost 30 years.
Tory leader Coun Michael Winstanley described it as an "historic" change for the party's fortunes in the borough.
But deposed opposition leader Coun Paul Tushingham of the Democratic Alliance said: "It's a blow but we remain steadfast."
It is thought to be the first time in the history of the authority that a sitting councillor has switched to the Tories.
Last week, in another success for the party, it was announced that Coun Henry Cadman will become Wigan's first Conservative Mayor in almost 25 years.
Coun Houlton, a care worker, won the Lowton East seat for the Community Action Party in 2006, and only recently learned that election law charges had been dropped by police after Labour made an official complaint to GMP about claims he made on YouTube.
In May this year Tory James Grundy unseated CAP's Sandy Franzen to take the other Lowton East seat from Community Action.
In an official statement, Coun Houlton said he had thought hard about the decision but concluded the best way to "achieve results and make things better" for Lowton and Wigan was as a member of Conservative Group.
He added: "I am not doing this to damage CAP even though I am saying goodbye. At the end of the day I was really unhappy with the way things were in the party and the council group, both of which have had their day.
"I have had an awful lot of abuse from certain members of my former party. I can't stand arguing with people and would much prefer to be allowed to get on with being a good councillor.
"People of Lowton East need representing by people who will treat them with respect and dignity and that is the Conservatives."
Democratic Alliance leader Coun Tushingham said Coun Houlton's decision was "regrettable" and believes it was influenced by external issues.
He continued: "I have no idea what promises have been made to him by the Conservatives or what has caused such a step change in his political ideals and the move away from what he stood for when first elected.
"I also have no idea how he will fit in with the policies of the Conservative Group given his political views.
"It would be churlish for me not to wish him well in his role as a councillor and I hope he will work hard for the people in his ward.
"Though a blow to our group, our policies and actions remain steadfast. We will continue to work hard at delivering good community services."
Leader of the Conservative group Coun Winstanley said Coun Houlton's defection was a "historic moment for the Conservative Group on Wigan Council."
He said: "The approach by Edward came out of the blue but never the less was very welcome indeed.
"It means that for the first time since the Metro was created in 1974 the Conservatives are the largest group behind Labour.
"I believe this is down to the responsible approach and principled opposition we have taken in opposing Labour and giving people a real alternative."
New ward colleague Coun James Grundy said he was "more than happy" with Coun Hulton's decision.
He said: "I have worked closely with Edward on a number of local projects.
"By working together we can make more of an impact and really help deliver for the residents."
But Community Action Party leader Peter Franzen said: "It is disappointing. He has betrayed not only his Community Action Party colleagues, who helped and supported him as a councillor, and with his serious personal legal issues, but also the trust of the voters of Lowton.
"If he had an ounce of integrity left Coun Houlton would resign his seat and stand for election under his true colours, whatever they may be."