While climate change hasn’t been a major issue in this year’s presidential election, one could say it's on the ballot in the Texas 21st Congressional District race.

Credit David Martin Davies Tom Wakely, Democratic candidate for TX CD-21, block walks with volunteers.

It’s a warm Sunday in late October and Tom Wakely is block-walking in north San Antonio.

The 63-year-old Democrat is running for Congress in the Congressional District 21 – a reliably Republican district that covers sections of San Antonio and south Austin, as well as the ruby red Hill Country.

He knocks on one front door and it’s answered by a smiling man who says “I already voted” before Wakely can say howdy.

“You already voted?” “I sure did.” “Who did you vote for? Did you vote Republican?” “I did.”

Credit David Martin Davies

This homeowner is polite to Wakely but he’s voting straight ticket Republican Party. Undeterred, the first-time candidate proceeds to the next house, all the while being carefully watched by an urban herd of white-tailed deer.

The next morning at the Comal County Republican Party headquarters in New Braunfels, it’s a different scene. Local GOP stalwarts are reveling in the October surprise – news of possible additional Hillary Clinton emails. One woman is wearing prison stripes as a political statement. There’s a cardboard cutout of a smiling Donald Trump, the GOP presidential nominee.

“It’s another example of Hillary Clinton and her aids not coming clean with the FBI,” said Rep. Lamar Smith. He is meeting with his Republican supporters as he seeks another re-election.

Credit David Martin Davies

The 69-year old Smith was first elected to Congress in 1986. With his seniority Smith has become the influential chairman of the House Science, Space and Technology committee, which, among other things, oversees all government environmental research. That includes the National Oceanic and Atmospheric Administration, (NOAA) which is seen as the government's authority on climate change data.

"The science committee has held many hearing on NOAA's troubled weather satellite program over the years," Smith said at a congressional hearing.

Critics say Smith has targeted NOAA due to climate change politics. He says they are manipulating their findings.

Smith disputes the dire predictions of catastrophic climate change and is using his chairmanship to threaten the head of NOAA with criminal charges if she did not release emails from scientists concerning a climate change study.

Democratic challenger Wakely calls Smith the Climate Change-Denier-in-Chief and he’s made it a key issue in his campaign.

“Climate change is the issue of our times. And it is the major issue. All these other issues – affordable housing – health care – those are all issues that need to be addressed but they become mute if the world goes to hell in a hand basket because of climate change,” he said.

Map of Texas Congressional District 21 which covers north San Antonio, South Austin and the Texas Hill Country

Smith says his re-election is not about climate change and when he talks with voters the topic rarely comes up.

“This is an election in my district about whether my constituents and my voters want to return someone who’s been effective and is conservative versus somebody who is an acolyte of Nancy Pelosi,” said Smith.

Wakely says he’s no acolyte of former speaker Pelosi – he’s an acolyte of Senator Bernie Sanders. Speaking at his home that he’s turned into a hospice for veterans, Wakely says he’s getting zero help from the Democratic Party –probably because he is such a long shot.

“I think they take a look at the historic voting patterns in the district and they make a decision,” he said.

All of Smith's 14 re-election races have been walkaways. He’s never won by less than 25 percent of the vote. The last Democrat to challenge Smith in 2012 took just 35 percent of the ballots.

But Wakely says times and the district are changing.

“That whole I-35 corridor is booming. Housing developments, new apartment complexes – so the whole demographics is changing – it’s now over 30 percent Hispanic,” he said.

And Wakely says he could ride the possible anti-Trump surge to victory. But Smith says Trump is winning big league and he’s a big Trump supporter.

“I think Trump helps and I’m certainly supporting him. I mean he really does represent the working men and women of America,” Smith said.

Credit David Martin Davies Tom Wakely at his home that he has turned into a hospice for veterans.

Nevertheless, those who care deeply about Climate Change are closely watching Congressional District 21.

“There’s no doubt a lot of responsibility is resting on the shoulders of the voters in the district," says Aseem Prakash, the director of the University of Washington Center for Environmental Politics. "And if they can cast a vote in a way that says the United States must take climate change seriously then I think they are going to send an important message."

Prakash says even if Wakely managed to unseat Smith it wouldn’t matter much in the political fight over climate change if the GOP maintains control of Congress.

Smith said he’s eager to get reelected for his 16th term and get back to work.

“I hope to be Chairman of the Science, Space and Technology committee for another two years,” he said.

Smith says he has investigations underway and there’s more work to be done to quote “hold this administration accountable.”

Also on the ballot for Congressional District 21 is a Green Party candidate -- Antonio "Tony" Diaz and a Libertarian -- Mark Loewe.