Senior Republican and Democratic members of the U.S. Congress told President Donald Trump on Friday they were concerned about Hungary's "downward democratic trajectory," ahead of Prime Minister Viktor Orban's visit to Washington Monday.

"In recent years, democracy in Hungary has significantly eroded. ... Under Orban, the election process has become less competitive and the judiciary is increasingly controlled by the state," Republican Senate Foreign Relations Committee Chairman Jim Risch and Bob Menendez, the panel's top Democrat, said in a letter to Trump.

The letter was also signed by Republican Senator Marco Rubio and Democratic Senator Jeanne Shaheen.

Several Democratic members of the House of Representatives, led by House Foreign Affairs Committee Chairman Eliot Engel, called on Trump to cancel his meeting with Orban, citing similar concerns as well as his anti-Semitic and xenophobic comments.

Orban is a nationalist leader who has often had conflicts with the European Union over his anti-immigration campaigns and judicial reforms. He clashed with the administration of then-U.S. President Barack Obama, a Democrat, over what critics said was an erosion of democratic values by his government.

The senators also said they were very concerned about the close relationship between Hungary, a NATO partner, and Russia. They said Hungary has failed to diversify its energy resources from Moscow and allowed Russia to exploit its visa system to evade U.S. sanctions.

They called the relocation of the International Investment Bank from Moscow to Budapest "an exercise in Russian power projection." And they said it was disturbing that Hungary rejected a U.S. extradition request for two arms dealers and instead sent them "to their freedom in Moscow."

The senators asked Trump to raise those concerns in his meeting with Orban and underscore U.S. support for the Hungarian people.

White House officials did not immediately respond to a request for comment on the letter.

However, a senior administration official told reporters at the White House that Orban's visit was part of a Trump administration strategy of re-engagement in Central and Eastern Europe, trying to encourage nations to work together and engage with NATO and neighbors like Ukraine.

"The point of this meeting is simply just to reinforce the strategic relationship between allies ... not necessarily to thrash out every issue on the bilateral agenda, which we have been doing constantly for the past two years," the official said.