1 March 2016 Last updated at 11:47 GMT
Twenty-nine people, including a woman pregnant with twins, were killed in the Real IRA attack in the County Tyrone town.
On Tuesday, the murder case against bricklayer Seamus Daly, from Jonesborough, County Armagh, collapsed in court.
Mr Daly, 45, had denying any involvement in the bombing.
Campaigners Michael Gallagher and Stanley McComb gave their reaction.
The families of some of the people killed in the 1998 Omagh bomb have said they feel "let down" by the criminal justice system after the collapse of the latest murder case.