DENVER — Democratic Colorado Sen. Mark Udall hasn’t said much publicly since Republican Congressman Cory Gardner stepped forward to challenge him this fall.

But what Udall said in a radio interview Wednesday — that he stands by his yes vote on the Affordable Care Act — is now the subject of a new web ad from Gardner’s campaign.

“Any regrets at all, the way this thing has played out? Would you still cast the same vote?” an interviewer asks Udall in the video.

“We did the right thing,” Udall responds. “I would do it again.”

The 30-second video ends with the sound of radio static and text that reads: “party-line politician Mark Udall.”

Gardner, and Republicans nationally, plan to make Obamacare a central issue in this fall’s midterm elections, having seen Democratic fortunes dip over the last several months since the major piece of the new health care law, the online marketplaces, has been implemented and led to confusion and anger from those who’ve seen their old policies cancelled and premiums go up.

Udall’s increased vulnerability, borne out by polls toward the end of last year, is the main reason Gardner, who had a safe House seat he could have held for decades, took the plunge into the Senate race last month.

Democrats, meanwhile, have been looking to focus the race on social issues, with Udall attacking Gardner for his support of personhood, prompting the Republican to flip on that issue late last week.

Udall blasts Gardner: “You can’t fake Colorado values”

On Thursday, the Udall campaign blasted Gardner for “attempt[ing] to shed his skin on every issue under the sun” in a story by Politico’s Manu Raju taking stock of the Colorado Senate race.

Udall’s campaign pointed to anecdote, reported by Raju, about Gardner “lying” to a woman on Medicare “about protecting her health care.”

Here’s the piece of the article detailing Gardner’s visit to a Meals on Wheels facility in Loveland:

At the facility, Gardner shook volunteers’ hands and peppered them with questions, tagging along as meals were being delivered to the underprivileged. Even then, though, Gardner’s political views came into question.

A woman on a breathing tube made clear that she was relying on Medicaid to survive.

“I was on my death bed, literally,” she told Gardner. “It kept me alive.”

“We got to protect Medicaid,” Gardner told her.

Asked about that episode later, Gardner made clear he opposed Colorado’s move to expand Medicaid under Obamacare. “I don’t know how Colorado is going to pay for it,” he said.

“Colorado wants a Senator who will do anything for Colorado, not a politician who will do anything to get elected,” said the email from Udall’s spokesman, Chris Harris.

“You can’t fake Colorado values, which is why Coloradans will see through Gardner’s desperate attempt to hide his life’s work from voters.”