The Israeli government’s decision to bar elected members of the United States Congress from entering Israel and the West Bank is bad enough. But Donald Trump’s cheerleading for the move to prevent a visit by Representatives Rashida Tlaib and Ilhan Omar is one of the most atrocious acts of his atrocious presidency.

Amid reports that Israeli Prime Minister Benjamin Netanyahu would bar the Democratic congresswomen from entering the country for a trip that was supposed to start Saturday, Trump was literally egging Netanyahu on. “It would show great weakness if Israel allowed Rep. Omar and Rep.Tlaib to visit,” the president tweeted Thursday morning. “They hate Israel & all Jewish people, & there is nothing that can be said or done to change their minds. Minnesota and Michigan will have a hard time putting them back in office. They are a disgrace!”

Not long after Trump tweeted, it was reported that Israeli Deputy Foreign Minister Tzipi Hotovely had told an Israeli radio station, “The decision has been made, the decision is not to allow them to enter.”

The Israeli government’s move reverses a stance announced last month by the Israeli ambassador to the United States, Ron Dermer, who had said, “Out of respect for the U.S. Congress and the great alliance between Israel and America, we would not deny entry to any member of Congress into Israel.” And Israeli leaders who oppose Netanyahu’s approach were quick to say that this decision damages the country’s image. Decrying the move as “both fundamentally wrong and diplomatically foolish,” Israeli Knesset member Tamar Zandberg, a former leader of the left-leaning Meretz party, declared, “A democratic country can’t deny entry to elected officials of a friendly democracy.” Veteran Knesset member Ahmad Tibi, a longtime leader of the Arab Movement for Change (Ta’al) party, said, “Often it is hard for Palestinians to explain to the American public why Netanyahu’s policy is so disastrous. Now, that task is easier.”

In the United States, Representative Jerry Nadler said, ”It is utterly egregious for the Israeli government to deny entry to two sitting members of the United States Congress. The close relationship enjoyed by the United States and Israel should extend to all its government representatives, regardless of their views on specific issues or policies. This decision undermines the ability for our two allied countries to have the frank, open and, at times, difficult discussions that we must have in order to ensure Israel remains a secure and democratic nation.”

But if this decision harms the image of Israel, it is also harms the image of the United States. “Make no mistake, the Israeli government just barred two elected members of the U.S. Congress from an official trip just to appease President Trump’s fragile ego,” explained former secretary of housing and urban development Julián Castro, a 2020 Democratic presidential contender. “This is appalling.”

Appalling, and profoundly damaging to the system of separated powers that governs the United States. Indeed, it is hard to imagine a greater threat to the system of checks and balances than a circumstance where the president pressures allies to block travel by members of Congress.

By advocating for another country to bar a visit by elected members of Congress, Trump is actively seeking to undermine the Congress. Make that very actively. The Israeli newspaper Haaretz reported Thursday that “assessments in the United States indicate that Israel was inspired to reconsider its decision due to pressure from the White House. Channel 13 News reported earlier this week that U.S. President Donald Trump had expressed disappointment over Netanyahu’s decision to let the two lawmakers enter Israel.” Barak Ravid, the senior diplomatic correspondent for Israel’s Channel 13 News, tweeted Thursday morning, “There is only one reason for Netanyahu’s backtracking today—the pressure from Donald Trump.”

Trump’s hectoring on this issue has been shameful, and by all evidence it extends from his crude (and constantly restated) bias against the first two Muslim-American women elected to the Congress: Tlaib, whose parents were Palestinian immigrants, and Omar, who came to the United States as a refugee from Somalia. (Israel on Friday said it would permit Tlaib to visit her 90-year-old grandmother, who lives in the occupied West Bank, if she accepted restrictions on political statements made during the trip. Tlaib rejected the limits, saying: “Silencing me and treating me like a criminal is not what she wants for me. It would kill a piece of me. I have decided that visiting my grandmother under these oppressive conditions stands against everything I believe in–fighting against racism, oppression and injustice.”)

The Democratic representatives have criticized Israel policies and expressed support for the Boycott, Divestment, and Sanctions movement that seeks to pressure Israel to change its policies. But even those who disagree with the positions taken by Tlaib and Omar—including the American Israel Public Affairs Committee, which criticized the travel ban—recognize that elected members of the United State Congress have a right and a responsibility to visit regions of the world where US policies are felt.

A particular concern involves Omar’s role as a member of the House Foreign Affairs Committee who serves on its subcommittees on Africa, Global Health, Global Human Rights, and International Organizations and Oversight and Investigations. An outspoken human rights advocate, Omar has been critical of the policies of many countries, including Saudi Arabia. Setting a precedent that she can be banned from traveling because of her criticism of a country’s policies is atrocious. And that the president of the United States would promote such a ban is doubly atrocious.

No matter what a president, any president, thinks about the opinions of members of Congress, it is fundamentally wrong to use the prestige and power of the office to advocate against the ability of members of Congress to travel and gather information. Beto O’Rourke got it right Thursday morning. “President Trump,” he said, “you show great weakness every single day—when you attack women of color, when you degrade the office of the president, and when you ask our allies to stoop to your level.”