The top two candidates vying for Texas' 21st Congressional district have sparred over the economy, regulation and immigration.

Republican Chip Roy and Democrat Joseph Kopser are looking to replace longtime Republican Congressman Lamar Smith. Smith is retiring after serving 16 terms.

Kopser is an army veteran and tech entrepreneur. Roy is a former senior staffer for Sen. Ted Cruz. The district includes parts of San Antonio, Austin and the Hill County. While it's been solidly in Republican hands since the 1970s, Democrats are energized about their chances because its political demographics have shifted over the past few elections.

Roy said he's not worried.

“I don’t think about it as being a Republican or Democratic district,” Roy said in an interview on Capital Tonight. “They want someone who’s going to go there (Washington) and fight for them, and make sure that the things they believe in -- a secure border, health care freedom, making sure that we have a balanced budget and strong economy so they have jobs.”

Roy also said he supports Texas Attorney General Ken Paxton’s position that the Deferred Action for Childhood Arrivals program is unconstitutional.

“I think that we can find solutions forward that will secure the border, provide an immigration system that works and that we can figure out ways to deal with the kids here that are in that class.”

Click the video link above to watch the full interview with Roy, including his bid to rein in the federal government if elected.