In the short time that it’s been playing music, Denver quartet the Congress has been entertaining crowds around the globe with its unique blend of roots rock and Southern R&B. The Congress’ debut self-titled EP gained critical acclaim since its March 2010 release, allowing the group to play festivals including Wakarusa, Jazz Aspen Snowmass and Groovefest, among many others. The group’s songs even have been used for a fundraising campaign on CNN for Haitian earthquake relief. Planning to release its first full-length album in early 2012, the band has focused its attention on perfecting the live show, something that’s attracting fans left and right. Find out why the Congress is unimpeachable when it performs at the National on Friday, Dec. 23, at 7 p.m. $15. 612-1900.