Health care is emerging as the most important issue for Democrats as they try to hone their midterm election message. Republicans promised, but failed, to repeal and replace Obamacare. Yet premiums are still rising.

While some Republicans are preparing a last-ditch effort to tackle Obamacare this summer, Democrats are preparing to tie the GOP to the higher costs of the system they created, unilaterally, in 2009-2010.

They have good reason to think it will work. In many of the special elections Democrats have won over the past several months — notably, Alabama’s Senate race — health care has been a key component of their message.

In the absence of a health care policy of their own, some Republicans are attacking Democrats’ health care policies. That task is made easier in California, where leading Democrats have embraced the idea that the government should provide for everyone’s health insurance — even though no one has yet devised a way to pay for such a scheme.

The Hill notes:

Republicans are seizing on Democratic demands for a single-payer health system as an attack line in California, arguing that candidates backing the issue spearheaded by Sen. Bernie Sanders (I-Vt.) are out of step with their districts.

“My opponent wants socialized medicine and government-run healthcare,” Rep. Mimi Walters (Calif.), a GOP incumbent and top Democratic target, told The Hill. “The district does not support it.”

Walters represents one of seven GOP-held seats in California that Hillary Clinton won in 2016 that Democrats are seeking to take back. If Republicans lose those seats, it would greatly increase the chances that the GOP loses the House.

Republicans say that Democratic candidates might have done well in crowded primaries running on “Medicare for All” when they needed to move to the left. But they say that position will be a major drag in a general election decided by more centrist voters.

Democrats are trying to blunt the Republican attack — which they fear is effective — by coaching their candidates not to use the term “single-payer.” Instead, as Politico reported last week, they are using the phrase “Medicare for All” to describe their proposals, “to draw strong connections with the popular seniors’ health program.”

California is crucial to the battle for control of the U.S. House in 2018, as Democrats hope to win up to seven seats in the Golden State that are currently held by Republicans but where Hillary Clinton won more votes in 2016. The Democrats need 23 seats nationwide to take control of the House and put Nancy Pelosi back in the Speaker’s chair.

Joel B. Pollak is Senior Editor-at-Large at Breitbart News. He was named to Forward’s 50 “most influential” Jews in 2017. He is the co-author of How Trump Won: The Inside Story of a Revolution, which is available from Regnery. Follow him on Twitter at @joelpollak.