Jen Psaki, a CNN political commentator, was the White House communications director and State Department spokeswoman during the Obama administration. She is vice president of communications and strategy at the Carnegie Endowment for International Peace. Follow her at @jrpsaki. The opinions expressed in this commentary are solely those of the author. Read more opinion articles at CNN.

(CNN)Senate Republicans should be careful what they wish for — and that includes South Carolina Sen. Lindsey Graham, who this weekend said out loud what many of his fellow Republicans are thinking. “I don’t want to speculate, but I think appointing judges is a high priority for me in 2020,” he told Greta Van Susteren, host of “Full Court Press.”

Should a Supreme Court seat open up, President Donald Trump and Senate Republicans have five months to jam through another conservative. If the next available seat is vacated by one of the liberal justices, then their new appointee could cement the nine-member court’s conservative tilt for decades to come.

Don’t think that Senate Majority Leader Mitch McConnell is going to press pause and abide by the election year rule he designed when denying Judge Merrick Garland a Senate hearing in 2016. Just consider the nomination of Justin Walker, a district court judge with limited experience on the bench who McConnell is aggressively pushing through the Senate confirmation process during a pandemic.

Few Democrats want to talk about the possibility of a liberal vacancy. After all, Justice Ruth Bader Ginsburg, the oldest justice at age 87, is an icon who broke through gender barriers to become one of the most influential and committed progressive voices on the Supreme Court in history. As a proud owner of a “Notorious RBG” shirt, I get it. But remember, she and Justice Stephen Breyer, another liberal member of the court in his 80s, cannot be justices forever.

And if Republicans are talking about this, Democrats should be, too.

I was the communications director in the White House when then-President Barack Obama nominated Garland. We naively thought that someone who had been confirmed to the DC Court of Appeals with 76 votes in the Senate would face some opposition — but would ultimately be confirmed.

Clearly, we were wrong. McConnell was not going to let that happen. Not only did Garland not get a hearing, he barely had any meetings with Republicans.

Democrats have every right to still be bitter about this. I still am.

But Democrats should also turn that bitterness into action — and take a lesson from Trump and McConnell, making the next Supreme Court vacancy a centerpiece of the 2020 election. Unlike in 2016, when the Garland nomination was not mentioned during the Democratic National Convention, it should get top billing this year.

The good news is that Democrats have a lot to work with. Unlike in 2018, when there were a number of vulnerable Senate Democrats up for re-election in red states (like North Dakota and Missouri) where all Republicans had to do was win reliably Republican voters, this year McConnell’s majority hinges on vulnerable Republicans winning states with a plethora of moderate suburban voters — the same voters who helped Democrats win back the House in the midterms.

More specifically, McConnell has to defend the seats of Maine Sen. Susan Collins, whose approval rating sunk following her vote to confirm Justice Brett Kavanaugh. He also has to protect Colorado Sen. Cory Gardner, who represents an increasingly purple state with a Democratic opponent — former Gov. John Hickenlooper — who is leading by double digits in early state polling, and Arizona Sen. Martha McSally, who not only lost her first Senate race, but is now running against a highly admired astronaut.

And while Republicans won some Senate races in reliably red states in 2018, Kavanaugh’s confirmation was a drag on Republican House candidates in districts that look a lot more like the states where 2020 will be decided.

Republican incumbents are already running with Trump at the top of the ticket during a global pandemic that has already cost more than 90,000 American lives — and millions of jobs. But they will also be running at a time when the Supreme Court is considering a Republican-led lawsuit to end the Affordable Care Act. If there is a vacancy on the Supreme Court, a vote for a Republican incumbent would be a vote for killing the Affordable Care Act, which is more popular now than it has ever been, according to the Kaiser Family Foundation.

Democrats should be clear that confirmation of another Trump judge could be the death knell of the Affordable Care Act, which Trump is currently asking the Supreme Court to overturn. In other words, they should make this vote the 2020 version of the ACA-repeal votes that contributed to the downfall of so many Republican members of Congress in 2018.

Anyone voting to confirm a Trump nominee is voting to kick tens of millions of Americans off their health care in the middle of a pandemic that’s reminding families everywhere how important access to care really is.

And Democrats should not let Senate decorum get in the way. It’s basic campaign 101 — when a candidate is down, you don’t let up. You deliver the clear knockout punch.

When talking about the Supreme Court, Democrats too often spend time trying to look reasonable — saying they need to consider all the details of a nominee’s record. There’s a time and a place for that, but we shouldn’t pretend that there’s any question what kind of nominee Trump’s going to pick. He’s told us and shown us time and again: he’ll pick a judge hand-selected by the Federalist Society, a conservative legal organization, who will side with him on issues like ending the Affordable Care Act, expanding executive authority and overturning the landmark abortion case of Roe v. Wade.

Finally, Democrats can’t hem and haw for weeks. Democratic Senate candidates should announce the stakes of this election immediately and begin to mobilize grassroots opposition, putting vulnerable Senate Republicans in the hot seat.

No one on the Democratic side wants to be fighting a conservative replacement to Ginsburg, perhaps because they want her to live forever. But preserving her legacy also means being prepared for the fight. And if Graham and McConnell are getting ready, Democrats must be, too.