Rubio and Van Hollen: Our elections are in danger. Congress must defend them.

While the 2016 election may have left our country divided on many issues, it exposed one critical problem that should unite all Americans: Our democratic process is vulnerable to attacks by hostile foreign powers. As our intelligence community unanimously assessed, Russia used social media channels to influence and mislead voters. It also hacked political campaign committees and local elections boards in a brazen attempt to undermine and subvert our elections.

There is no reason to think this meddling will be an isolated incident. In fact, we expect the threat will grow in future years. The United States must do everything possible to prevent these attacks in the future — and lay out the consequences well in advance of our next elections. Tuesday, we are introducing bipartisan legislation to do just that.

Our bill, the Defending Elections from Threats by Establishing Redlines Act, would send a powerful message to any foreign actor seeking to disrupt our elections: If you attack American candidates, campaigns or voting infrastructure, you will face severe consequences.

We believe that clearly outlining our deterrence strategy will send an important message to any adversary contemplating interfering in a future U.S. election. This legislation uses key national security tools to dissuade hostile foreign powers from meddling in our elections by ensuring the costs outweigh the benefits.

To start, we must ensure there is a system for continued monitoring and reporting on foreign threats to elections — and clear punishments if attacks occur. Our legislation would require the director of national intelligence to issue a determination to Congress, within one month after every federal election, on whether any foreign government had interfered in that election.

The Deter Act also spells out actions that would elicit retaliation. A foreign power cannot purchase advertisements to influence an election, including online ads, or use social and traditional media — such as the thousands of trolls and botnets deployed by the Kremlin — to spread significant amounts of false information to Americans. They also cannot hack, leak or modify election and campaign infrastructure, including voter registration databases and campaign emails. Finally, no foreign power can block or otherwise hinder access to elections infrastructure, such as websites providing information on polling locations.

Because we know Russia has already employed many of these actions, the Deter Act would mandate a set of severe sanctions if the director of national intelligence should determine that the Kremlin had once again interfered in a U.S. federal election. Within 10 days of such a determination, our bill would require the administration to impose sanctions on major sectors of the Russian economy, including finance, energy, defense, metals and mining. It would also block the assets of every senior Russian political figure or oligarch and prevent them from entering the United States. We also would require the administration to work with the European Union to enlist its support in adopting a sanctions regimen to broaden the impact.

These sanctions are far tougher than any action taken on Russia to date and would send an unequivocal message to the Kremlin: We will not tolerate an attack on our democracy.

But Russia is not our only concern. The director of national intelligence has identified China, Iran and North Korea as our other major foreign government cyberthreats, and they may also seek to exploit U.S. vulnerabilities in the next election cycle. That is why our legislation would require the administration to present Congress with a plan for preventing interference in our elections for each of these countries, plus any other foreign state of significant concern, within 90 days of the Deter Act becoming law.

We cannot underscore enough the urgency of this issue. In less than a year, Americans will head to the ballot box for the midterm elections. Our next presidential election will be here before we know it. It is unrealistic to think we can simply sit back and hope that we do not face another attack by a hostile foreign power.

We and other lawmakers stand willing to work with the administration to develop additional cybersecurity policies that will help protect our election infrastructure and develop a broad-based deterrence strategy. The United States must be fully prepared to defend our country, and the Deter Act would put in place a bipartisan, comprehensive strategy to prevent future attacks on our elections. We urge Congress to pass it without delay.

Chris Van Hollen, a Democrat, represents Maryland in the U.S. Senate.

Marco Rubio, a Republican, represents Florida in the U.S. Senate.