Colorado’s Democratic candidate for governor Jared Polis apologized on Twitter Friday for calling his support of a carbon tax “fake news.” Polis came out in favor of a state carbon tax last week in a 9NEWS debate.

Polis made his “fake news” accusation at a Colorado Chamber of Commerce candidate forum Thursday night. His comments were first reported by The Colorado Sun.

Asked about his support for a carbon tax, Polis responded:

“It’s not on my agenda, we’ve never talked about it. It’s kind of fake news.”

While Polis’ energy plan on his campaign website does not make mention of a carbon tax, he said he would support a similar plan when asked by 9NEWS anchor Kyle Clark in our debate last Wednesday, hosted with The Coloradoan.

Clark pointed out that Polis has supported a federal carbon tax in the past. When asked if Colorado should become the first state in the country to implement such a tax, Polis said he’s looked at the idea of reducing individuals’ income tax and using revenue from a carbon tax to supplement the budget:

“I want to be clear, this would be revenue neutral. We’re not talking about increasing or decreasing the size of government. We’re talking about how we pay for government. And yes, if we’re talking about would I rather tax polluters than individual hardworking families earning $50,000, or $100,000, or $200,000, of course – I’d rather that we have a broader tax base and bring down rates for Colorado residents.”

WATCH: Jared Polis' comments on carbon tax in 9NEWS gubernatorial debate

A Twitter user called out Polis for using the phrase most frequently used by President Trump to describe media reports he doesn't like.

“You used the term fake news. That’s embarrassing,” the person wrote, prompting the apology from Polis.

“You are correct,” he wrote. “In these challenging times when journalists are under attack, candidates and elected officials shouldn’t make jokes that could be construed as denigrating real media. I apologize and will try harder to refrain from doing so in the future.”

WATCH: 9NEWS gubernatorial debate