A liberal attempt to revive the so-called public option — a government-run insurance plan to shore up gaps in the Affordable Care Act — is opening old wounds between the Democratic Party’s liberal and moderate wings.

Thirty-three mostly liberal Democrats, including all the Senate leadership, have signed onto a nonbinding Senate resolution introduced last Friday to add the public option to Obamacare, arguing that it is needed to fix problems with the president’s signature health care law.


But missing from the list are vice-presidential nominee Tim Kaine and a half-dozen other moderates who face reelection in 2018 — when the map that favors Democrats this year will flip to favor Republicans.

Kaine’s absence is especially striking since Hillary Clinton embraced the public option in July.

A campaign spokesperson said Kaine is “supportive of a workable public option for health care insurance,” even though he has not co-sponsored the resolution.

But other moderate Democratic senators made it clear that they remain uncomfortable with a government-run health program.

Sen. Jon Tester, a moderate Montana Democrat up for reelection in 2018, said the focus should be on working “on a bipartisan basis to fix Obamacare.”

“Until we get to the point that we’re willing to work together on that … we’re going to continue to see problems,” Tester said.

Sen. Heidi Heitkamp (D-N.D.), who won her 2012 election with 50.24 percent of the vote and is expected to face a tight race in 2018, called the public-option debate a “distraction.”

“We’ve had a whole lot of discussion about what’s going to happen to Obamacare but … we aren’t having discussions [about how we deliver higher-quality care at lower costs] because we keep discussing how we’re going to fund it,” she said.

The resistance of moderate Democrats led to the scuttling of the public option when it was first debated as a potential part of the ACA in 2009.

Now, the continued divide between liberals and moderates could be a preview of coming battles if Clinton were to become president and liberals mounted a serious effort to add a public option to Obamacare.

Since the ACA was conceived, liberals have insisted that a government-run health insurer would pressure private insurers to reduce premiums. Now, progressives say, many of the ACA’s flaws could be repaired with a public option, which would essentially be a new plan offered on the Obamacare insurance exchanges, some of which are down to only one or two private insurers.

Clinton has repeatedly said on the campaign trail that she would “defend” the Affordable Care Act if elected president. Her campaign website pledges that she will “build on its success to bring the promise of affordable health care to more people and make a ‘public option’ possible.”

Sen. Jeff Merkley (D-Ore.), who is spearheading the effort, said that besides Clinton’s endorsement, rising premiums and the high-profile withdrawal of Aetna and United Healthcare from several exchanges makes the issue ripe for discussion.

“We’re right in the middle of the presidential campaign, and I think it’s important during this campaign and [House and Senate races] to have a conversation about having competition in all the exchanges across the country,” Merkley said.

He downplayed the lack of support from moderates and said he has not run the resolution by the Clinton campaign. He pointed out that all of the Democratic leaders have signed on as cosponsors.

“So there is a wide range of folks — folks from states that have big insurance companies’ headquarters, like Connecticut — folks who don’t. It’s a broad spectrum,” he said. “We’re only a couple days into this.”

Adam Green, co-founder of the Progressive Change Campaign Committee, which is championing the resolution, said the goal is to build momentum to enact a public option next year. Green said he’s happy with 33 co-sponsors so far and hopeful that moderate lawmakers from rural states are drawn to the idea of more competition among insurers.

“Rural states have big problems with competition, and having a public option would actually be really popular in those states,” he said.

But some red-state Democrats are skeptical.

Sen. Claire McCaskill (D-Mo.), who is also due to face voters in 2018, said she’s open to discussing the public option “but I want to make sure that we’ve done everything to make the market work before we turn to that.”

Republicans are already trying to frame the public option as “more Obamacare,” a preview of the battle that could come if Democrats are in a position to pursue the proposal.

“Democrats actually introduced legislation last week calling for Obamacare 2.0, a new government-run health plan,” Senate Majority Leader Mitch McConnell said Wednesday. “And there are good reasons why so many of their own caucus won’t support it. It’s insulting to the millions of Americans who continue to watch their premiums spike — after Democrats said they’d be lower.”