The Capitol dome in Washington. (Susan Walsh/Associated Press)

Republicans should be on the lookout. While we try to muddle through repealing and replacing Obamacare, Democrats are sharpening their message on health care. In their race to the left, Democrats are increasingly calling for a full-fledged single-payer system. And considering Republican credibility on repeal-and-replace is damaged, if not shot, the Democrats’ message will be compelling to a lot of voters who sense nothing but confusion from the GOP. The momentum is shifting, and the stakes are getting higher for Republicans.

As we all know, in politics, a bumper sticker beats an essay. With the “single-payer, universal health care” catchphrase, Democrats are beginning to use their simple “bumper stickers” more frequently. And it’s not just talk. Last Thursday, the liberal California state Senate voted to support a plan calling for the enactment of a single-payer system. The New York Times also reports that “a number of the party’s potential 2020 presidential contenders, including Senators Cory Booker of New Jersey and Kamala Harris of California, have signaled support for some version of universal government care.” It looks as though there will probably be a consensus position among Democrats running in 2020 in support of a single-payer system.

In the House of Representatives as well, 112 of the 193 Democrats have co-sponsored Rep. John Conyers Jr.’s (D-Mich.) proposal for a single-payer system. “Until recently,” the New York Times reports, “the bill had attracted a fraction of that support.”

This new reality begs the question: Could it be that Republicans are on the brink of defending Obamacare as the only practical alternative to the Democrats’ march toward socialized medicine? On its surface, single-payer, universal health care will be hard to beat in the face of rising premiums and onerous deductibles that Republicans can’t seem to do anything about. A lot of voters will think that Democrats are trying to give them free health care and that Republicans are against it.

Looking back to last year’s presidential race, it was easy for Republicans to dismiss Sen. Bernie Sanders’s (I-Vt.) call for single-payer, universal health care. After all, the Democratic National Committee opposed him and his far-left ideas just as much as Republicans did. But the State of California — however liberal it may be — is not a rogue, one-off former candidate trying to uproot and destroy the status quo.

At a time when Democrats appear ready to coat their fleet of environmentally friendly and eco-conscious vehicles with “single-payer, universal health care” bumper stickers, I don’t even know what the GOP bumper sticker says.

Republicans are bogged down trying to fix the broken Obamacare system while Democrats advance a simple, albeit misguided message. So, how should the GOP fight back?

As has been the case for much of 2017, Republicans need presidential leadership to guide the way forward. The White House must do more than simply be willing to sign what the GOP-led Congress sends to the president’s desk. The president needs to define Republican priorities on health care and explain what they mean to families throughout the country. Otherwise, we will become overwhelmed and labeled as the party with no solution.

If Republicans don’t act fast, Democrats will pitch their plan for single-payer, universal health care as a choice between something that costs individuals less vs. more, that is simpler vs. more complicated, that leads to greater equality vs. more inequality. And in this fight, Republicans cannot just become the party of no. We cannot just complain about how hard the process is in the face of a growing liberal tsunami of single-payer nirvana.

The question for Republicans is: How will this all play out? If Republicans fail to stand up and speak with clarity, we may be forced to defend the remnants of Obamacare as the best option to ward off socialized medicine. The public senses confusion, and the Democrats sense an opportunity. Time is running out.