Imagine that the Democrats sweep the Republicans out of the U.S. House of Representatives in the midterm elections of 2018. Given President Trump’s current approval ratings, that is a likely prospect unless something changes in the GOP’s favor over the next year and a half. If the GOP remains vulnerable enough to lose the House in a Democratic wave, then this scenario probably also includes several more major missteps by the White House and in particular by the president of the United States. Perhaps the Republicans retain control of the U.S. Senate, but that is hardly assured.

It seems almost certain that the activist base of a newly empowered Democratic House majority would demand the launch of an impeachment inquiry against the president, and it seems plausible that the leadership of the House would be inclined to go along with that demand. After all, the air is already thick with impeachment talk. On Sunday, Laurence Tribe argued that President Trump must be impeached for obstruction of justice. Today Phillip Carter proposed draft language for seven possible articles of impeachment, for everything from alleged Emoluments Clause violations to "failing to timely appoint officers . . . to administer the nation's federal agencies."

For some, the president was so obviously unfit for office that he should have been blocked by the presidential electors in December of 2016. I thought that was inappropriate and unwise, as I argued here. For many more, the president has been vulnerable to impeachment since the day of his inauguration, and the tension between his personal business holdings and the Constitution’s emoluments clause is sufficient to justify an impeachment. I have not generally agreed with that view. The two most recent missteps—the removal of FBI director James Comey and the revelation of classified foreign intelligence information to Russian government officials—provide even more materials to lay the foundations for impeachment charges against the president. Undoubtedly, if left to his own devices, the president would provide yet more possible reasons to support an impeachment over the coming months. Whether an impeachment vote would actually be justified would depend on what a careful inquiry into the facts revealed.

But for the moment, let’s set aside the question of whether an impeachment is justified under the terms of the Constitution. The political fact is that a Democratic House would likely want to impeach the president, and there is a reasonable chance that a Democratic House will emerge before the president’s term of office has expired.

Presidential impeachments should not be partisan affairs. It is relatively easy to mobilize an impeachment vote. Only a majority in the House of Representatives is necessary to support an impeachment, and the majority party can go it alone if they so choose in the House. A conviction in an impeachment trial in the U.S. Senate, however, requires a two-thirds vote. It is exceedingly rare for one party to have enough votes in the Senate to generate a conviction on its own. If a president is going to be removed from office through impeachment, it is essential that at least some members of the president’s own party agree in that judgment.

An impeachment without a removal is itself damaging. Congress would be tied up for an extended period of time in the impeachment proceedings. If the president escapes conviction, he would nonetheless be rendered an ineffective lame duck. His domestic agenda would undoubtedly ground to a halt, and his standing in the arena of foreign affairs would be significantly diminished. The political recriminations from pursuing impeachment charges when a conviction could not be obtained would be severe.

An impeachment effort primarily supported by the partisan foes of a president threatens to undermine the stability of the political system as a whole. If the president’s supporters remain largely unconvinced that an impeachment is warranted, then an impeachment effort would seem to be little more than a partisan effort to undo a legitimate election. If the people are to have confidence in the political system, they must at the very least have confidence that there will be a peaceful transfer of power when the incumbents lose an election and that the electoral losers will accept the electoral results and adopt the role of the loyal opposition until the next election. If the impeachment power is perceived to be little more than a partisan tool for undermining elected officials and overturning election results, then the value of elections for resolving our political disagreements is significantly reduced. We do not want to be in a situation in which neither side trusts the other to continue adhering to the most basic democratic norms of abiding by election results.

It is hard to reach bipartisan agreement on an impeachment. The Jeffersonians did not persuade Federalists when they impeached federal judges at the beginning of the nineteenth century. The Republicans did not persuade Democrats when they impeached President Andrew Johnson. The Republicans did not persuade Democrats when they impeached President Bill Clinton. President Richard Nixon resigned when Republican opposition to his impeachment collapsed. In our current era of highly polarized politics, it is even more difficult to find common ground in which to consider impeachable offenses. The stakes of empowering the opposition are seen as too high; the distrust of the other side is too great. That does not mean that an impeachment might never be justified if agreement cannot be reached across the partisan divide. Partisans will often have incentives to rally around their vulnerable ally, and the measure of an impeachable offense cannot simply be reduced to whether the closest friends of an impeachment target are willing to concede its necessity.

Despite the difficulty, some measure of bipartisanship should be the goal before the impeachment option is taken seriously. In our current circumstances, that means Democrats should be cautious about moving forward with impeachment efforts without winning some support from Republican lawmakers. It also means that Republican lawmakers should listen carefully to what their Democratic colleagues are telling them. By not playing a sufficiently active role as watchdog against abuses from the executive branch, Republicans could wind up feeding a political dynamic that leads to a partisan impeachment that makes everyone worse off and damages the constitutional system as a whole. Partisans have a responsibility to take seriously the possibility of abuses and mistakes by their allies as well as their foes and to act decisively to ameliorate those problems when they arise.

Avoiding the nightmare scenario of a partisan impeachment by the other side means keeping your own house in order. Doing so requires taking the steps needed to reduce the likelihood of impeachable offenses occurring and addressing any problems that arise by less drastic but effective means so that impeachment does not seem to be the only option. Hoping that the problem will simply go away or take care of itself is likely to just set the stage for a much worse outcome in the future.