Tony Essalih joined Cornerstone in 2011 as a co-lead of the firm's flagship Texas office in Houston. He spent 12 years on Capitol Hill and came to Cornerstone from the office of Congressman John Culberson (R-Houston). Tony worked for Congressman Culberson for 10 years, the last five as his chief of staff. Prior to becoming chief of staff, Tony served in a variety of capacities including legislative assistant, legislative director, communications director, and deputy chief of staff. He spent eight years in Washington, D.C. before relocating to Houston in 2007.

As chief of staff, Tony was responsible for guiding the day-to-day operations of the Congressman's Washington and Houston offices, and oversaw a 15-member staff under a fixed budget. Outside of the office, he served as the principal liaison to the Congressman's campaign committee and provided strategic counsel and advice related to his re-election efforts. Tony's areas of policy expertise include transportation, energy, budget and appropriations. Tony also led outreach efforts and served as an emissary on behalf of the Congressman with state lawmakers in Austin and local elected officials in Houston.

Prior to Culberson's election in 2001, Tony worked as a legislative assistant for Congressman Culberson's predecessor, former House Ways and Means Committee Chairman Bill Archer. Tony's began his tenure on Capitol Hill with former House Natural Resources Committee Chairman Doc Hastings.

Tony has advised and assisted numerous local, state, and federal campaigns. He serves on the board of the National InterFaith Foundation, the Advisory Board for the Houston Technology Center, spent two years on the Board of the Spring Branch Medical Center and was a member of Houston Mayor Annise Parker's transition team in 2010.

Tony was born and raised in Fredericksburg, VA and received his B.A. in Political Science from Mary Washington College. He was a member of Mary Washington's NCAA semifinalist men's soccer team. He lives in Houston and has two angelic daughters, Grace and Libby.

Mark Harmon joined Cornerstone in December of 2024, expanding the firm's South Carolina office and solidifying our southern reach and capabilities.

Prior to joining Cornerstone, Mark served as Principal at The Harmon Consulting Group, LLC, where he provided contractual lobbying and consulting services by representing multiple clients before the legislative and executive branches of the South Carolina state government. Previously, Mark worked at Maynard Nexsen, PC, formerly Nexsen Pruet, LLC, as Government Affairs Advisor, also providing contractual lobbying and consulting services at the state level.

Before shifting to contract lobbying and consulting, Mark served as Executive Director of the America Petroleum Institute of South Carolina, advocating on behalf of the oil and natural gas industry before the state and federal government. In this role, he also coordinated with state agencies to ensure oil and natural gas operators were able to get products into high-demand areas during hurricanes and natural disasters. Additionally, Mark cultivated relationships with several of the state's Historically Black Colleges and Universities to promote STEM opportunities in oil and gas.

Prior to his work with the American Petroleum Institute, Mark served as the Vice President of Government Affairs and Public Policy for the South Carolina Chamber of Commerce. Harmon represented the state's business community and led an internal team responsible for generating the Chamber's public policy agenda, implementation strategy and social media outreach.

Before his time with the Chamber of Commerce, Mark served as the Executive Director of the South Carolina Senate Republican Caucus, where he organized campaigns, led ethics compliance and financial accounting and acted as liaison between Caucus supporters and senators to ensure all parties' interests were represented. As part of this role, Mark served as the day-to-day policy advisor to Senate Republican Caucus members and organized legislative session events and annual retreats for members and contributors. During his tenure, the Caucus gained seats and expanded its majority.

Mark received his Bachelor of Science in Ceramic and Materials Engineering from Clemson University.

Craig Holzheauser brings to Cornerstone years of involvement in Texas state and local politics. The son of a state representative, Craig went to work in the private sector after college before beginning a political career at the state capitol in 2012.

Working as a legislative consultant, managing the campaigns of House and Senate members, and serving as legislative director and then committee director of the House Committee on Public Health in his first year of employment, Craig is goal oriented and proven himself to be a quick study. Craig has a keen political intuition and a knack for developing the type of relationships that matter in campaigns, service of an elected official, or success for his clients.

A native of Victoria, Texas, Craig holds a Bachelor of Science in Construction Science from Texas A&M University.

Mark Yates joined Cornerstone in July 2021 as a principal in the firm's Oklahoma City office. His experience in public policy includes working with various industries through statewide campaigns, legislative engagement, media relations, and public speaking. Mark has been successful navigating complex and challenging initiatives on behalf of the clean energy and agriculture industries.

Mark previously served as vice president at Advanced Power Alliance (APA) where he represented leading domestic and international companies in the renewable energy sector. While in this role, he managed the association's regional public policy strategy, communications strategy, and membership recruitment efforts. Mark served a major role in shaping legislative and regulatory policy within the most important energy region in the country.

Prior to APA, Mark worked at the Oklahoma Farm Bureau, where he led membership recruitment initiatives, mobilized a statewide grassroots campaign, and lobbied for rural issues on behalf of the nearly 90,000 farmers and ranchers.

Before his time with the Farm Bureau, Mark was a professional educator in the Oklahoma public school system for 11 years. Along with his teaching experience, Mark also had administrative experience serving as a federal programs director for Plainview Public Schools in Ardmore, OK.

Mark is a graduate of East Central University in Ada, OK and holds a bachelor's degree in History and master's in Secondary Administration. Mark and his wife Stacy reside in Edmond, OK where they are active in their community and have two children, Londyn and Steele.

Max Moll joined the Cornerstone Public Affairs team April of 2023, bringing a public affairs and strategic communications presence to Cornerstone's Texas offices. In his previous role as chief engagement officer at the Houston Independent School District, he oversaw government relations, communications, family and community engagement and board relations for the nation's eighth largest school district. He also oversaw the district's legislative affairs work and external lobby team, ensuring alignment and execution of district's legislative priorities. In addition, he represented the district with external stakeholders, in traditional and digital media appearances, and on panels and other various speaking opportunities. He was also the lead spokesperson for the district and main point of contact for elected officials, advocacy groups and private industry.

Prior to working at HISD, Max served as the chief communications officer & deputy director for the Office of the Houston City Controller, Chris B. Brown. He spearheaded all communications initiatives for the Office of the City Controller, working across the City of Houston's 22 departments to help unify external and internal communications. Max served as liaison between Controller's Office and the city's investors, developing key external messaging relating to investment strategy, portfolio performance, and maintaining key relationships with city's investor base. In addition, and in partnership with the Controller's Office Treasury Division, Max helped oversee the city's Environmental, Social, and Governance (ESG) investments, helping grow the portfolio to over $950 million.

Max also served as the chief of staff to the CEO of the Houston Hispanic Chamber of Commerce, where he oversaw the development and execution of the Chamber's public affairs and community outreach efforts, legislative advocacy campaigns and external affairs projects. Also, he served as the main point of contact for media, securing comprehensive coverage and managing all media relationships on behalf of the Chamber and its members.

He holds a master's in business administration from Boston University, master's in political management from George Washington University, and a bachelor's in mass communication from LSU.

Ross Giesinger brings over a decade of legislative experience at the Texas Capitol to the Cornerstone team, having served for six legislative sessions in both the Texas House and Senate.

Most recently, Ross worked as a policy advisor to Dade Phelan, Speaker of the Texas House, of Representatives, during the 87th Regular Session, where he assisted with the passage of over 80 pieces of legislation. Additionally, Ross drafted and managed several bills filed in response to Winter Storm Uri, including SB 3, one of the most comprehensive energy reforms in Texas in the last 20 years.

Prior to his time in the House, Ross spent several years working as general counsel and legislative director for Sen. Lois Kolkhorst (R-TX) and as the director of the Senate Committee on Health and Human Services. While at the Senate, Ross assisted with the passage of nearly 300 bills and worked to obtain funds for a variety of initiatives, including legislation that secured permanent funding for Texas State Parks.

Ross began his career at the legislature in 2010 as a drafting attorney for the Texas Legislative Council. During his time with the state, he has drafted thousands of pieces of legislation, allowing him to develop expertise in a wide variety of subject areas, including energy, healthcare, water, land use and development, transportation, insurance, labor, agriculture, wildlife, taxation, and state budgeting.

Ross is a graduate of the University of Texas at Austin and Southern Methodist University's Dedman School of Law. He is a member of the Austin Young Lawyers Association and was recently elected to serve on the Council of the Texas State Bar's Legislative and Campaign Law Section. Ross also serves as a Steward of the Wild for the Texas Parks and Wildlife Department and has been active in the Austin Ballet Guild, the Trail Foundation, and CCA. He and his wife Courtney live in Austin with their young son Henry.