(Ilana Panich-Linsman/Reuters)

We’re now a month away from the inauguration of Donald Trump, and only a couple of weeks away from the swearing-in of a new Congress, one that at long last knows that it no longer has to worry that its bills will be vetoed by a president from the other party. As you might expect, many Republicans are giddy with excitement over all the new laws they’ll be able to pass, as they remake America into a paradise of liberty, prosperity and strong old-fashioned values. But there’s danger lurking there, too, because a whole bunch of promises they’ve made in recent years are now going to have to be kept, and they won’t have a Democratic president to use as an excuse for avoiding ideologically important but politically perilous actions.

For now I want to focus on just one of those actions: defunding Planned Parenthood. This is going to be one of the first items on the Republican agenda, not because the leadership necessarily relishes having a fight over it, but because Republican activists are already demanding it, and they will not be denied. This is likely to be big trouble for Republicans — indeed, it could be their first major legislative defeat next year.

Just to clarify, “defunding” Planned Parenthood has nothing to do with abortion, because federal funds can’t go to abortion services. The funds in question are mostly Medicaid reimbursements: a woman on Medicaid goes to a Planned Parenthood clinic for a gynecological exam, a cancer screening, or some other health service, and Medicaid pays the bill. What Republicans want to do is bar women on Medicaid from getting their health care from Planned Parenthood. They passed such a provision last year, and President Obama vetoed it.

After Donald Trump's many shifting comments about women's health and reproductive rights, some women are worried about what will happen under the new administration. (Jenny Starrs/The Washington Post)

Courts have struck down state laws that tried to prevent Medicaid patients from using Planned Parenthood, and the Obama administration just instituted a federal rule barring states from denying Medicaid patients the ability to get care from the organization’s clinics. But that could be overridden by a new law Congress passed and President Trump signed.

But is that the first fight this new Congress wants to have? Polls show that clear majorities, ranging from around 55 to 65 percent of the public, oppose the Republican effort to defund Planned Parenthood. And it’s a loser in two ways: Republicans want to do something unpopular in the service of a different but equally unpopular goal (making abortions illegal or impossible to obtain).

Yet they have almost no choice. After committing themselves so publicly to the defunding — and almost shutting down the government in order to do it — Republicans have to move on it early, or risk a revolt from antiabortion activists who are always suspicious that their priorities are going to be put on the back burner when the GOP takes power. Yet despite the party’s total control of government, there are multiple points at which this effort could fail.

First, there’s the matter of the filibuster, which Senate Democrats would definitely use to stop any effort to defund Planned Parenthood. Republicans will have 52 seats in the new Senate, and it’s unlikely they could get even a single Democrat to join them on this, let alone the eight they’d need to overcome a filibuster.

But they could try to attach it to a bill passed through “reconciliation” — which requires only a 50-vote majority — most likely a partial repeal of the Affordable Care Act. There are two problems there, however. Reconciliation bills can deal directly with only questions that have budgetary impact, and a ban on Planned Parenthood funding doesn’t increase or decrease the deficit, it merely tells women that they can’t go to certain clinics. Furthermore, it’s not certain that Republicans could even get the 50 votes they’d need, if they could somehow get a ruling from the parliamentarian that a defunding measure qualified for reconciliation. Maine’s Susan Collins is already on record opposing it, as is Lisa Murkowski of Alaska. Democrats would need to find only one more Republican to stop it.

Republican presidential front-runner Donald Trump has repeatedly stated that he supports Planned Parenthood's women's health programs – just not abortion. (Peter Stevenson/The Washington Post)

Finally, there’s no telling where Trump will fall down on this issue, since his ideas about Planned Parenthood are muddied, to say the least — during the campaign he praised the group yet said he also supported defunding it. But his vice president, Mike Pence, is one of the most virulently anti-choice politicians in America, so chances are that if a defunding measure made it to Trump’s desk, there would be enough people directly around him pressuring him that he’d sign it.

But it probably won’t reach Trump’s desk, which would mean the worst of all possible worlds for Republicans: They wouldn’t get the policy victory they want, but they’d suffer the backlash from trying to do so. And if they do manage to pass it, the news will be filled with horror stories from women who used to rely on Planned Parenthood for their health care but now can’t find providers, all because a bunch of antiabortion zealots in Washington wanted to tell them which doctor they could go to.

It’s another reminder that when you’re in the opposition, making promises is easy. You can hold symbolic votes, secure in the knowledge that you won’t be held accountable for your actions. But once you have power, you have to come through for those who stood by you — even if it means doing something that will make the broader public very unhappy. Planned Parenthood funding may be the first time Republicans find themselves in that position in 2017, but it won’t be the last.