Complex sentence: The Official Reform Party of NewYork State has been in existence since 2008 and has endorsed and/or nominated many individuals for many offices, including, but not limited to the Reform Party of NYS ran a candidate for Mayor in New York City in 2013.
Split into simpler sentences: The official Reform Party of New York State has been in existence since 2008 and has endorsed and/or nominated many individuals for many offices. The Reform Party of NYS ran a candidate for Mayor in New York City in 2013.