What do candidates propose to prevent the next lawless presidency?

First came the announcement that the upcoming G7 summit would be conducted at President Donald Trump’s Doral resort outside Miami, a clear case of the president using his office to enrich himself and his family.

Then came the president’s acting chief of staff Mick Mulvaney’s confirmation that there was indeed a quid pro quo in Trump’s request for Ukraine to investigate Joe Biden, a clear case of the president using his office to the benefit of his re-election campaign.

Both of these events happened on the 1,000th day of Trump’s presidency, which like so many days before it had revealed illegal and inappropriate behavior by this unfit and morally bankrupt president.

And even though Mulvaney made a pathetic attempt to reverse his comment and Trump eventually reconsidered on the G7 site, what his presidency has shown more than anything is how ill prepared our system is to deal with a chief executive who is intentionally lawless and endlessly corrupt. The informal, time-honored standards of presidential behavior and decorum mean nothing to Trump, who’s blown through these guardrails and is now becoming increasingly brazen in violating the Constitution and the law.

That being the case, we urge every candidate seeking to unseat Trump in 2020 to issue concrete proposals on how they will work with Congress to establish legal limits protecting against any future presidential abuse of power.

This will go against presidential impulses, as chief executives tend to expand power rather than limit it. But our system never anticipated the kind of active criminal behavior and self dealing that Trump has committed, so it’s critical to put new rules in place.

The reason is simple: Now that Trump has shown how to turn the presidency into a nakedly corrupt enterprise, and revealed the weaknesses of the system, we have to strengthen the system before another criminal president arrives and either replicates Trump’s behavior or takes it even a step further.

Hopefully, one of Trump’s opponents will be tasked with repairing the massive damage that Trump and his servile GOP leadership has done. That being the case, we need to know what kinds of measures they propose to make those repairs — and we need them to make that a prominent point of their platforms.

Let Trump run against that, assuming he’s not impeached.

Let him try to explain why any president would oppose stricter anti-nepotism rules, stronger restrictions on profiting off of his office, the same clear set of standards for professional behavior that would apply to the CEO of any reputable corporation, a requirement to respond to subpoenas from congressional investigators, a requirement to divulge records and transcripts of conversations in a timely fashion, and so forth.

Other presidents have recognized that Americans expect them to serve with honor, with respect for the office and in the interest of everyone living in the U.S.

This one does none of that. It’s up to his opponents to show Americans how they will prevent another president from also wiping his feet on the office.

Rep. Dina Titus, D-Nev., summed up Trump’s behavior well in reaction to the White House announcement about the G7 summit, which she correctly described as showing “intent to violate the law and ignore the Constitution.”

“The only logical conclusion,” Titus said in a news release, “is that President Trump is proud to be the most corrupt, lawless president in modern American history.”

Titus couldn’t have been more correct. Trump shows it constantly.

Now, his opponents should show how they would prevent another thug from following in his footsteps.