Over the past year, I’ve spent hours listening to witnesses talk about the events of the 2016 campaign. The House Intelligence Committee, on which I sit, has been investigating Russian interference in the election. Multiple members of Donald Trump’s campaign, businesses, and family, I’ve learned, were contacted by individuals linked to the Russian government—but none of them, so far as we know, reported these contacts to law-enforcement agencies.

For years, America has helped protect against terrorist attacks by telling Americans, “If you see something, say something.” The same should go for protecting our elections against foreign interference. Speaking up when you see it in action shouldn’t be optional—which is why I’m introducing a bill this week to make it a legal obligation to report efforts at foreign interference.

In the most obvious instance, Donald Trump Jr. received an email promising him secret “dirt” on Donald Trump’s 2016 opponent, former Secretary of State Hillary Clinton. Trump Jr. was told that Russia was offering this information as part of its support for his father’s candidacy. Instead of reacting with concern or alarm that a foreign power was trying to manipulate a United States election, Trump Jr. said he would “love” to get his hands on this information. He and his colleagues—then-Trump-campaign chair Paul Manafort and Trump’s son-in-law, Jared Kushner—met with a woman represented to him as an agent of the Russian government at Trump Tower, two years ago this Saturday.

George Papadopoulos, Carter Page, and Roger Stone also met or communicated with Russian nationals or with individuals suspected by American intelligence agencies of having ties to Russian intelligence, some of whom offered covert foreign aid to the campaign. Others associated with the Trump campaign did as well. None of them saw fit to notify the FBI of these contacts, either.

Although the House investigation was marred by Republican partisanship, and was prematurely and shamefully brought to an end by the president’s supporters on the committee, it did reveal this widespread unwillingness to inform law-enforcement agencies of the Russian efforts. Had anyone raised the alarm about this outreach, Russia’s efforts to interfere with the election might have been discovered and countered much earlier than they were. Instead, we are still picking up the pieces, and still vulnerable to foreign interference in our 2018 midterm elections.

Now that we have this knowledge, we have a responsibility to act on it so that this never happens again. To ignore this is to cede our democracy’s cornerstone—our free and fair elections—to our foreign adversaries. It was Russia supporting a Republican this time; it could be some other entity helping Democrats next time. This isn’t a partisan issue: No matter the players, it can’t be tolerated.

That’s why the Duty to Report Act would explicitly require candidates and campaigns to notify the FBI if anyone representing a foreign power offers dirt on that candidate’s opponents. More specifically, the legislation would make it a crime for candidates, their immediate family, or people involved with their campaign to fail to notify the FBI if any of them are told about, are offered, or receive in an unsolicited way nonpublic, materially significant information about another person running for the same office, when they know or recklessly disregard that the source is a foreign power or agent of a foreign power.

The bill would apply only when the information is about a candidate seeking the same office, both because that seems the likeliest scenario for foreign interference, and to avoid having the law to cover innocuous conversations people may have about contests in which they’re not involved. And I specified “know or recklessly disregard” to avoid leaving space for disingenuousness. What you know might be debatable, but if it walks like a spy, talks like a spy, and acts like a spy, you must assume that it’s a spy and act accordingly.

Most of us probably hoped this would be common sense, but unfortunately, it seems we must specify it. This isn’t meant as a rebuke to President Trump or as an effort to relitigate the 2016 election—it’s a preventative, defensive measure for the future.

In addition to enshrining this duty to report in federal law, our political parties should make a firm public pact that stolen or illegally hacked materials will not be used in our campaigns. The Democratic Congressional Campaign Committee has already made this public commitment; the National Republican Campaign Committee has reportedly been more circumspect, telling The Atlantic that it is “open to working with anyone to tackle cybersecurity issues.”

This should be a no-brainer. This isn’t about Republicans and Democrats—it’s about Americans standing together to proclaim that they won’t accept foreign efforts to taint electoral politics. To resist such a joint statement is to contribute to the very divisions America’s adversaries seek to exploit in our society.

Holding office often requires swearing an oath to support and defend the Constitution of the United States against all enemies, foreign and domestic. Running for office should include accepting responsibility for this, too, so that our democratic republic’s underpinnings can remain strong for generations to come.