The Republican plan to replace Obamacare is the "most unpopular legislation in three decades," according to a report Friday by Axios.

It has worse public approval than Obamacare had when Congress passed it and lower approval than President Bill Clinton's 1990s health-care reform push, according to the report.

The GOP effort had an average 28.2 percent approval rating in polls from March to May, Axios said, citing research from an MIT political science professor "who compiled polling data from Roper Center on major legislation Congress has passed since 1990."

The House passed its heavily criticized replacement plan in May. Senate Republicans are now trying to win skeptical senators' support to pass a similar plan.

Pushing or voting for an unpopular plan potentially makes Republican lawmakers more vulnerable in the 2018 midterm elections.

Senate Majority Leader Mitch McConnell acknowledged Thursday that a bill to fix Obamacare insurance marketplaces — a likely bipartisan effort — will be needed if the replacement effort fails. Conservative GOP Sen. Ted Cruz of Texas has proposed a change to allow companies that sell Obamacare plans to also offer cheaper, bare-bones options, though it is unclear if that would be enough to muster the votes needed to pass legislation.

The public has not warmed to the Senate plan in recent polling — three separate surveys late last month showed the Senate plan with 17 percent, 16 percent and 12 percent approval.

Read the full Axios report here.