Dennis spent much of his childhood in Clovis, growing up the son of an Air Force officer stationed at Cannon AFB.
In 1995, he received a teaching degree from Eastern NM University in Portales and continued his studies in the Washington, DC, area-- earning his master's degree while working for US Senator Pete Domenici (R) on Capitol Hill. He returned home to serve as a Field Representative for US Rep. Bill Redmond (R) in Roosevelt, Curry, Quay, Harding, Union, and Colfax Counties.
He joined the Texico Municipal Schools faculty in 1999 and spent more than eight years there, teaching English and math and coaching baseball and volleyball. In 2007, he accepted a position with the Tucumcari Public Schools as assistant superintendent. It was there that he met Rochelle Hodge, a Tucumcari native, who became his wife in June 2008. The couple now live in Logan, where he serves as Superintendent of the Logan Municipal Schools. He and Rochelle have three daughters and one son.
Dennis first sought elective office in 2004, when he was elected to a 4-year term on the Public Education Commission (formerly the NM State Board of Education). He served as the Commission's chairman for 2 years. Then, in 2008, he was elected State Representative for District 67 in northeastern New Mexico and was subsequently re-elected in 2010, 2012, 2014, and 2016. He retired from the legislature in January 2019.
While in office, Dennis served on several committees, most notably the House Education Committee and the House Rules & Order of Business Committee. During the interim period between legislative sessions, he served many interim committees, including the Legislative Education Study Committee (LESC), and he was privileged to chair this key committee in 2016-2017.