Sources say the Leeds-based retailer, which has around 120 stores and employs some 2,500 staff, is poised to enter administration.
After undergoing rapid expansion about 10 years ago, it has since seen sales slacken off.
The group is reported to have already lined up the business services firm Ernst & Young to handle the administration.
The company focuses on the youth fashion market, which is fiercely competitive and under pressure.
"Operating towards the value end of the market should have placed the retailer in a strong position to take advantage of the consumer trend towards low-cost fashion," said Anusha Couttigane, from retail consultancy Conlumino.
"However, its target youth market has been the hardest hit demographic of the recession and it has struggled to appeal to them as effectively as rivals such as Primark, Asos or H&M.
"Fashion is a fast-moving industry where brand loyalty is fickle and Republic has failed to keep up with some pretty fierce competitors," she said.
If Republic does appoint administrators, it will be following in the footsteps of a list of High Street stalwarts.
These include the music retailer HMV, the camera group Jessops and the DVD and games rental company, Blockbuster.
"It's the worst post-Christmas period we've seen in a long time," said Matthew Hopkinson from the Local Data Company.
Republic is owned by private equity firm TPG, which bought the company in 2010 in a deal thought to be worth about Â£300m.
According to Anusha Couttigane, TPG had been trying to sell off some stores and persuade landlords to agree to lower rents.
"In light of this, news of its administration suggests that attempts to renegotiate monthly payments have failed, bringing the business to a complete standstill and landlords facing the prospect of more vacant units on the High Street."
Matthew Hopkinson said that while some stores may be snapped up, the vast majority of them are in shopping centres, which would be difficult to fill.
"HMV and others have also been sitting in shopping centres and therefore I think the number of units which have gone in the last few months in shopping centres will make it far harder than 12 months to refill them," he said.
Republic began selling denim clothing in Leeds in 1986 and since then has grown to supply both men and women with clothing brands including G-Star, Diesel and Firetrap.
Its chairman, Andy Bond, who was a former boss of Asda, is said to have left the company last week after two years.
Its current chief executive is the former boss of TK Maxx, Paul Sweetenham.
Fears are growing for the future of clothing chain Republic.